Investments, Debt and Equity Securities [Abstract] Schedule of Investments and Equity in Earnings of Unconsolidated Affiliates Equity Method Investments [Table Text Block] Schedule of Carrying Amounts and Fair Values of Available for Sale Securities Schedule of Available-for-sale Securities Reconciliation [Table Text Block] Cover [Abstract] Document Type Document Type Document Quarterly Report Document Quarterly Report Document Period End Date Document Period End Date Document Transition Report Document Transition Report Entity File Number Entity File Number Entity Registrant Name Entity Registrant Name Entity Incorporation, State or Country Code Entity Incorporation, State or Country Code Entity Tax Identification Number Entity Tax Identification Number Entity Address, Address Line One Entity Address, Address Line One Entity Address, City or Town Entity Address, City or Town Entity Address, State or Province Entity Address, State or Province Entity Address, Postal Zip Code Entity Address, Postal Zip Code City Area Code City Area Code Local Phone Number Local Phone Number Title of 12(b) Security Title of 12(b) Security Trading Symbol Trading Symbol Security Exchange Name Security Exchange Name Entity Current Reporting Status Entity Current Reporting Status Entity Interactive Data Current Entity Interactive Data Current Entity Filer Category Entity Filer Category Entity Small Business Entity Small Business Entity Emerging Growth Company Entity Emerging Growth Company Entity Shell Company Entity Shell Company Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Amendment Flag Amendment Flag Document Fiscal Year Focus Document Fiscal Year Focus Document Fiscal Period Focus Document Fiscal Period Focus Entity Central Index Key Entity Central Index Key Current Fiscal Year End Date Current Fiscal Year End Date Goodwill and Intangible Assets Disclosure [Abstract] Goodwill and Other Intangible Assets Goodwill and Intangible Assets Disclosure [Text Block] Debt Disclosure [Abstract] Schedule of Notes Payable Schedule of Long-term Debt Instruments [Table Text Block] Gross Principal Maturities of Notes Payable Schedule of Maturities of Long-term Debt [Table Text Block] Schedule of Goodwill [Table] Schedule of Goodwill [Table] Segments [Axis] Segments [Axis] Segments [Domain] Segments [Domain] Restaurant Group Restaurant Group [Member] Restaurant Group [Member] Corporate and Other Corporate and Other [Member] Goodwill [Line Items] Goodwill [Line Items] Goodwill [Roll Forward] Goodwill [Roll Forward] Balance, December 31, 2019 Goodwill Goodwill impairment Goodwill, Impairment Loss Deconsolidation of Blue Ribbon Goodwill, Decrease Related To Deconsolidation Goodwill, Decrease Related To Deconsolidation Balance, March 31, 2020 Supplemental Cash Flow Elements [Abstract] Cash paid during the period: Supplemental Cash Flow Information [Abstract] Interest Interest Paid, Excluding Capitalized Interest, Operating Activities Income taxes Income Taxes Paid, Net Operating leases Cash Paid For Operating Leases Cash Paid For Operating Leases Non-cash investing and financing activities: Cash Flow, Noncash Investing and Financing Activities Disclosure [Abstract] Lease liabilities recognized in exchange for new lease right-of-use assets Right-of-Use Asset Obtained in Exchange for Operating Lease Liability Organization, Consolidation and Presentation of Financial Statements [Abstract] Schedule of Variable Interest Entities [Table] Schedule of Variable Interest Entities [Table] Investments by Consolidated and Nonconsolidated Entities [Axis] Investments by Consolidated and Nonconsolidated Entities [Axis] Investments by Consolidated and Nonconsolidated Entities [Axis] Investments by Consolidated and Nonconsolidated Entities [Domain] Investments by Consolidated and Nonconsolidated Entities [Domain] [Domain] for Investments by Consolidated and Nonconsolidated Entities [Axis] Variable Interest Entity, Not Primary Beneficiary Variable Interest Entity, Not Primary Beneficiary [Member] Counterparty Name [Axis] Counterparty Name [Axis] Counterparty Name [Domain] Counterparty Name [Domain] Blue Ribbon American Blue Ribbon Holdings, LLC [Member] American Blue Ribbon Holdings, LLC [Member] Balance Sheet Location [Axis] Balance Sheet Location [Axis] Balance Sheet Location [Domain] Balance Sheet Location [Domain] Prepaid Expenses and Other Current Assets Prepaid Expenses and Other Current Assets [Member] Variable Interest Entity [Line Items] Variable Interest Entity [Line Items] Total Assets Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets Maximum Exposure Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount Schedule of Goodwill Schedule of Goodwill [Table Text Block] Segment Reporting [Abstract] Schedule of Segment Reporting Information, by Segment [Table] Schedule of Segment Reporting Information, by Segment [Table] Dun & Bradstreet Dun And Bradstreet Corporation [Member] Dun And Bradstreet Corporation [Member] Product and Service [Axis] Product and Service [Axis] Product and Service [Domain] Product and Service [Domain] Restaurant revenue Restaurant Sales [Member] Restaurant Sales [Member] Other operating revenue Total Other Operating Revenue [Member] Total Other Operating Revenue [Member] Consolidation Items [Axis] Consolidation Items [Axis] Consolidation Items [Domain] Consolidation Items [Domain] Operating Segments Operating Segments [Member] Dun & Bradstreet Elimination Intersegment Eliminations [Member] Segment Reporting Information [Line Items] Segment Reporting Information [Line Items] Revenues from external customers Revenue from Contract with Customer, Excluding Assessed Tax Interest, investment and other income, including realized and other gains and losses, net Investment Income, Nonoperating Total revenues and other income Revenues Depreciation and amortization Depreciation, Depletion and Amortization, Nonproduction Interest expense Interest Expense (Loss) earnings before income taxes and equity in earnings (losses) of unconsolidated affiliates Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest Income tax (benefit) expense Income Tax Expense (Benefit) Earnings before equity in losses of unconsolidated affiliates Income (Loss) From Continuing Operations Before Minority Interest And Income (Loss) On Equity Method Investments, Net Of Income Tax Income (Loss) From Continuing Operations Before Minority Interest And Income (Loss) On Equity Method Investments, Net Of Income Tax Equity in (losses) earnings of unconsolidated affiliates Income (Loss) from Equity Method Investments Earnings (loss) from continuing operations Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest Assets Assets Goodwill Revenue from Contract with Customer [Abstract] Trade receivables, net Accounts Receivable, after Allowance for Credit Loss Deferred revenue (contract liabilities) Contract with Customer, Liability Revenue recognized that was included in deferred revenue Contract with Customer, Liability, Revenue Recognized Subsidiary or Equity Method Investee, Sale of Stock by Subsidiary or Equity Investee [Table] Subsidiary or Equity Method Investee, Sale of Stock by Subsidiary or Equity Investee [Table] Financial Instrument [Axis] Financial Instrument [Axis] Financial Instruments [Domain] Financial Instruments [Domain] Ceridian Ceridian [Member] Ceridian [Member] Scenario [Axis] Scenario [Axis] Scenario [Domain] Scenario [Domain] Forecast Forecast [Member] Related Party [Axis] Related Party [Axis] Related Party [Domain] Related Party [Domain] Equity Method Investee Equity Method Investee [Member] Investment, Name [Axis] Investment, Name [Axis] Investment, Name [Domain] Investment, Name [Domain] AmeriLife AmeriLife Joint Venture [Member] Equity Funding To AmeriLife Joint Venture [Member] Equity Fund Limited Partnership, Equity Fund [Member] Limited Partnership, Equity Fund [Member] Subsequent Event Type [Axis] Subsequent Event Type [Axis] Subsequent Event Type [Domain] Subsequent Event Type [Domain] Subsequent Event Subsequent Event [Member] Legal Entity [Axis] Legal Entity [Axis] Entity [Domain] Entity [Domain] Cannae and Other Investors Cannae, THL And Other Investors [Member] Cannae, THL And Other Investors [Member] Subsidiary, Sale of Stock [Line Items] Subsidiary, Sale of Stock [Line Items] Sale of stock (in shares) Sale of Stock, Number of Shares Issued in Transaction Proceeds from sale of stock Sale of Stock, Consideration Received on Transaction Gain on sale of stock in equity method investment Equity Method Investment, Realized Gain (Loss) on Disposal Owned investment (in shares) Investment Owned, Balance, Shares Outstanding voting equity Equity Method Investment, Ownership Percentage Investment in Ceridian Equity Securities, FV-NI Unrealized gain upon change in accounting Equity Securities, FV-NI, Unrealized Gain Debtor-in-possession financing to be provided Debtor-In-Possession Financing, Commitment To Fund Affiliate, Maximum Amount Debtor-In-Possession Financing, Commitment To Fund Affiliate, Maximum Amount Realized and other gains and losses, net Nonoperating Gains (Losses) Investment in partnership Equity Method Investments Other than temporary impairment of investment Equity Method Investment, Other than Temporary Impairment Prepaid expenses and other current assets Prepaid Expense and Other Assets, Current Additional investment Payments to Acquire Equity Method Investments Basis of Financial Statements Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block] Principles of Consolidation and Basis of Presentation Consolidation, Policy [Policy Text Block] Management Estimates Use of Estimates, Policy [Policy Text Block] Earnings Per Share Earnings Per Share, Policy [Policy Text Block] Restricted Cash Cash and Cash Equivalents, Restricted Cash and Cash Equivalents, Policy [Policy Text Block] Recent Accounting Pronouncements New Accounting Pronouncements, Policy [Policy Text Block] Revenue Recognition Revenue from Contract with Customer [Policy Text Block] Schedule of Available-for-sale Securities [Table] Schedule of Available-for-sale Securities [Table] Measurement Basis [Axis] Measurement Basis [Axis] Fair Value Measurement [Domain] Fair Value Measurement [Domain] Portion at Fair Value Measurement Portion at Fair Value Measurement [Member] Carrying Value Reported Value Measurement [Member] Corporate debt securities Corporate Debt Securities [Member] Debt Securities, Available-for-sale [Line Items] Debt Securities, Available-for-sale [Line Items] Fixed maturity securities available for sale: Debt Securities, Available-for-sale, Fair Value to Amortized Cost [Abstract] Cost Basis Debt Securities, Available-for-sale, Amortized Cost Unrealized Gains Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax Unrealized Losses Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax Fair Value Debt Securities, Available-for-sale Statistical Measurement [Axis] Statistical Measurement [Axis] Statistical Measurement [Domain] Statistical Measurement [Domain] Minimum Minimum [Member] Maximum Maximum [Member] QOMPLX QOMPLX, Inc. [Member] QOMPLX, Inc. [Member] Investment without readily determinable fair value Equity Securities without Readily Determinable Fair Value, Amount Corporate debt securities, with maturity of less than one year Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, within One Year, Fair Value Corporate debt securities, with maturity of more than one year and less than five years Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, after One Through Five Years, Fair Value Other-than-temporary impairment charges related to corporate debt securities Other-than-temporary Impairment Loss, Debt Securities, Available-for-sale Debt securities held with previously recognized other than temporary impairment Available-for-sale, Amount Held with Previously Recognized Other Than Temporary Impairments Available-for-sale, Amount Held with Previously Recognized Other Than Temporary Impairments Statement of Financial Position [Abstract] ASSETS Assets [Abstract] Current assets: Assets, Current [Abstract] Cash and cash equivalents Cash and Cash Equivalents, at Carrying Value Short-term investments Short-term Investments Trade receivables Accounts Receivable, after Allowance for Credit Loss, Current Inventory Inventory, Net Total current assets Assets, Current Investment in Ceridian, at fair value - see Note A Equity Securities, FV-NI, Noncurrent Equity Securities, FV-NI, Noncurrent Investments in unconsolidated affiliates Lease assets Operating Lease, Right-of-Use Asset Property and equipment, net Property, Plant and Equipment, Net Other intangible assets, net Intangible Assets, Net (Excluding Goodwill) Goodwill Fixed maturity securities available for sale, at fair value Debt Securities, Available-for-sale, Noncurrent Deferred tax asset Deferred Income Tax Assets, Net Other long term investments and non-current assets Investments and Other Noncurrent Assets Total assets LIABILITIES AND EQUITY Liabilities and Equity [Abstract] Current liabilities: Liabilities, Current [Abstract] Accounts payable and other accrued liabilities, current Accounts Payable and Accrued Liabilities, Current Lease liabilities, current Operating Lease, Liability, Current Income taxes payable Accrued Income Taxes, Current Deferred revenue Contract with Customer, Liability, Current Notes payable, current Long-term Debt, Current Maturities Total current liabilities Liabilities, Current Lease liabilities, long term Operating Lease, Liability, Noncurrent Deferred tax liability Deferred Income Tax Liabilities, Net Notes payable, long term Long-term Debt, Excluding Current Maturities Accounts payable and other accrued liabilities, long term Accounts Payable and Accrued Liabilities, Noncurrent Total liabilities Liabilities Commitments and contingencies - see Note G Commitments and Contingencies Equity: Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest [Abstract] Cannae common stock, $0.0001 par value; authorized 115,000,000 shares as of March 31, 2020 and December 31, 2019; outstanding of 79,130,316 and 79,516,833 shares as of March 31, 2020 and December 31, 2019, respectively, and issued of 79,727,972 shares as of March 31, 2020 and December 31, 2019, respectively Common Stock, Value, Issued Preferred stock, $0.0001 par value; authorized 10,000,000 shares; issued and outstanding, none as of March 31, 2020 and December 31, 2019 Preferred Stock, Value, Issued Retained earnings Retained Earnings (Accumulated Deficit) Additional paid-in capital Additional Paid in Capital Less: Treasury stock, 597,656 and 211,139 shares as of March 31, 2020 and December 31, 2019, respectively, at cost Treasury Stock, Value Accumulated other comprehensive loss Accumulated Other Comprehensive Income (Loss), Net of Tax Total Cannae shareholders' equity Stockholders' Equity Attributable to Parent Noncontrolling interests Stockholders' Equity Attributable to Noncontrolling Interest Total equity Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest Total liabilities and equity Liabilities and Equity Antidilutive shares excluded from calculation of diluted earnings per share (in shares) Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount Segment Information Segment Reporting Disclosure [Text Block] Discontinued Operations and Disposal Groups [Abstract] Discontinued Operations Disposal Groups, Including Discontinued Operations, Disclosure [Text Block] Schedule of Indefinite-Lived Intangible Assets [Table] Schedule of Indefinite-Lived Intangible Assets [Table] Indefinite-lived Intangible Assets [Axis] Indefinite-lived Intangible Assets [Axis] Indefinite-lived Intangible Assets, Major Class Name [Domain] Indefinite-lived Intangible Assets, Major Class Name [Domain] Trade Names Trade Names [Member] Indefinite-lived Intangible Assets [Line Items] Indefinite-lived Intangible Assets [Line Items] Impairment of intangible assets Impairment of Intangible Assets, Indefinite-lived (Excluding Goodwill) Commitments and Contingencies Disclosure [Abstract] Loss Contingencies [Table] Loss Contingencies [Table] Loss Contingencies [Line Items] Loss Contingencies [Line Items] Accrual for legal proceedings Estimated Litigation Liability Supplemental Cash Flow Information Cash Flow, Supplemental Disclosures [Text Block] Variable Interest Entities Variable Interest Entity Disclosure [Text Block] Schedule of Related Party Transactions, by Related Party [Table] Schedule of Related Party Transactions, by Related Party [Table] Fidelity National Financial, Inc. Fidelity National Financial, Inc. [Member] Fidelity National Financial, Inc. [Member] Related Party Transaction [Line Items] Related Party Transaction [Line Items] Services Agreement, term Management Services Agreement, Term Management Services Agreement, Term Services Agreement, renewal term Management Services Agreement, Renewal Term Management Services Agreement, Renewal Term Revenue Recognition Revenue from Contract with Customer [Text Block] Disaggregation of Revenue Disaggregation of Revenue [Table Text Block] Contract Balances Contract with Customer, Asset and Liability [Table Text Block] Fair Value Disclosures [Abstract] Schedule of Fair Value of Assets and Liabilities Measured at Fair Value on a Recurring Basis Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block] Summary of Changes in the Fair Values of Level 3 Assets Measured on a Recurring Basis Fair Value, Assets Measured on Recurring Basis [Table Text Block] Schedule of Equity Method Investments [Table] Schedule of Equity Method Investments [Table] Equity Method Investment, Nonconsolidated Investee [Axis] Equity Method Investment, Nonconsolidated Investee [Axis] Equity Method Investment, Nonconsolidated Investee [Axis] Equity Method Investment, Nonconsolidated Investee [Domain] Equity Method Investment, Nonconsolidated Investee [Domain] [Domain] for Equity Method Investment, Nonconsolidated Investee [Axis] Unconsolidated affiliates Equity Method Investment, Nonconsolidated Investee Or Group Of Investees [Member] Equity Method Investment, Nonconsolidated Investee Or Group Of Investees [Member] Schedule of Equity Method Investments [Line Items] Schedule of Equity Method Investments [Line Items] Investments in Unconsolidated Affiliates Equity Method Investment, Summarized Financial Information [Abstract] Due from brokers and counterparties Receivables from Brokers-Dealers and Clearing Organizations Derivative contracts, at fair value Derivative Asset Other assets Other Assets Derivative contracts, at fair value Derivative Liability Capital received in advance Capital Received In Advance Capital Received In Advance Other liabilities Other Liabilities Net assets Net Assets Equity in Losses of Unconsolidated Affiliates Investment Company, Net Assets from Operations, Increase (Decrease) [Abstract] Total net investment loss Investment Income, Net Realized gain on securities and derivative contracts Realized Gain (Loss) on Securities And Derivatives Realized Gain (Loss) on Securities And Derivatives Change in unrealized loss on derivative contracts Unrealized Gain (Loss) on Derivatives Change in net assets from operations Investment Company, Net Assets from Operations, Increase (Decrease) Fair Value Measurements Fair Value Disclosures [Text Block] Dun & Bradstreet Condensed Combined Balance Sheets Total current assets Goodwill and other intangible assets, net Intangible Assets, Net (Including Goodwill) Other assets Other Assets, Noncurrent Current liabilities Long-term debt Long-term Debt Other non-current liabilities Other Liabilities, Noncurrent Preferred equity Temporary Equity, Carrying Amount, Including Portion Attributable to Noncontrolling Interests Total capital Condensed Combined Statements of Earnings Equity Method Investment, Summarized Financial Information, Income Statement [Abstract] Total revenues Loss before income taxes Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest Net earnings (loss) Net Income (Loss), Including Portion Attributable to Noncontrolling Interest Dividends attributable to preferred equity and noncontrolling interest expense Preferred Stock Dividends and Other Adjustments Net income (loss) attributable to Dun & Bradstreet Net Income (Loss) Available to Common Stockholders, Basic 2020 (remaining) Recorded Unconditional Purchase Obligation Due in Next Twelve Months 2020 Recorded Unconditional Purchase Obligation Due in Second Year 2021 Recorded Unconditional Purchase Obligation Due in Third Year 2022 Recorded Unconditional Purchase Obligation Due in Fourth Year 2023 Recorded Unconditional Purchase Obligation Due in Fifth Year Thereafter Recorded Unconditional Purchase Obligation Due after Fifth Year Total purchase commitments Recorded Unconditional Purchase Obligation Common stock, par value (in usd per share) Common Stock, Par or Stated Value Per Share Common stock authorized (in shares) Common Stock, Shares Authorized Common stock issued (in shares) Common Stock, Shares, Issued Common stock outstanding (in shares) Common Stock, Shares, Outstanding Preferred stock par value (in usd per share) Preferred Stock, Par or Stated Value Per Share Preferred stock authorized (in shares) Preferred Stock, Shares Authorized Preferred stock issued (in shares) Preferred Stock, Shares Issued Preferred stock outstanding (in shares) Preferred Stock, Shares Outstanding Treasury shares (in shares) Treasury Stock, Shares Fair Value, Recurring and Nonrecurring [Table] Fair Value, Recurring and Nonrecurring [Table] Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV [Domain] Fair Value Hierarchy and NAV [Domain] Level 3 Fair Value, Inputs, Level 3 [Member] Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] Fair value, beginning of period Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value Impairment Net valuation gain included in other comprehensive earnings Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss) Fair value, end of period Statement of Comprehensive Income [Abstract] Other comprehensive earnings (loss), net of tax: Other Comprehensive Income (Loss), Net of Tax [Abstract] Unrealized gain (loss) on investments and other financial instruments, net (excluding investments in unconsolidated affiliates) Other Comprehensive Income (Loss), Securities, Available-for-Sale, Unrealized Holding Gain (Loss) Arising During Period, after Tax Unrealized (loss) gain relating to investments in unconsolidated affiliates Other Comprehensive Income (Loss), Unrealized Holding Gain (Loss) On Equity Method Investments Arising During Period, Net Of Tax Other Comprehensive Income (Loss), Unrealized Holding Gain (Loss) On Equity Method Investments Arising During Period, Net Of Tax Reclassification adjustments for unrealized gains and losses on unconsolidated affiliates, net of tax, included in net earnings Other Comprehensive (Income) Loss, Reclassification Adjustment For Net Unrealized (Gains) Losses On Unconsolidated Affiliates And Other Investment Included In Net Earnings, Net Of Tax Other Comprehensive (Income) Loss, Reclassification Adjustment For Net Unrealized (Gains) Losses On Unconsolidated Affiliates and Other Investments Included In Net Earnings, Net of Tax Other comprehensive earnings Other Comprehensive Income (Loss), Net of Tax Comprehensive earnings (loss) Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest Less: Comprehensive loss attributable to noncontrolling interests Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest Comprehensive earnings (loss) attributable to Cannae Holdings, Inc. Comprehensive Income (Loss), Net of Tax, Attributable to Parent Unrealized gain (loss) on investments and other financial instruments, income tax expense (benefit) Other Comprehensive Income (Loss), Securities, Available-for-Sale, Unrealized Holding Gain (Loss) Arising During Period, Tax Unrealized (loss) gain relating to investments in unconsolidated affiliates, income tax (benefit) expense Other Comprehensive Income (Loss), Unrealized Holding Gain (Loss) On Equity Method Investments Arising During Period, Tax Other Comprehensive Income (Loss), Unrealized Holding Gain (Loss) On Equity Method Investments Arising During Period, Tax Reclassification adjustments for unrealized gains and losses on unconsolidated affiliates, tax expense Other Comprehensive Income Loss Reclassification Adjustment For Net Unrealized Gains Losses On Unconsolidated Affiliates, Net Of Tax, Include Net Earnings Other Comprehensive Income Loss Reclassification Adjustment For Net Unrealized Gains Losses On Unconsolidated Affiliates, Net Of Tax, Include Net Earnings Summary of Financial Information Concerning Reportable Segments Schedule of Segment Reporting Information, by Segment [Table Text Block] Leases [Abstract] Leases Lessee, Operating Leases [Text Block] 99 Restaurants Ninety-Nine Restaurants [Member] Ninety-Nine Restaurants [Member] Ownership interest, equity method investment Number of business records (more than) Number Of Business Records Number Of Business Records Level 1 Fair Value, Inputs, Level 1 [Member] Level 2 Fair Value, Inputs, Level 2 [Member] Measurement Input Type [Axis] Measurement Input Type [Axis] Measurement Input Type [Domain] Measurement Input Type [Domain] Discount Rate Measurement Input, Discount Rate [Member] Weighted Average Weighted Average [Member] Assets: Financial Instruments, Financial Assets, Balance Sheet Groupings [Abstract] Fixed-maturity securities available for sale: Investments, Fair Value Disclosure [Abstract] Corporate debt securities Total Assets, Fair Value Disclosure Discount rate Debt Securities, Available-for-sale, Measurement Input Schedule of Long-term Debt Instruments [Table] Schedule of Long-term Debt Instruments [Table] Debt Instrument [Axis] Debt Instrument [Axis] Debt Instrument, Name [Domain] Debt Instrument, Name [Domain] 99 Term Loan 99 Term Loan [Member] 99 Term Loan [Member] 99 Revolver 99 Restaurants Credit Facility [Member] 99 Restaurants Credit Facility [Member] 99 DLOC Loan Development Line Of Credit Loan [Member] Development Line Of Credit Loan [Member] Margin Facility Margin Loan Agreement [Member] Margin Loan Agreement [Member] Brasada Interstate Loans Brasada Credit Agreement [Member] Brasada Credit Agreement [Member] FNF Revolver Corporate Revolver Note [Member] Corporate Revolver Note [Member] Other Other Notes Payable [Member] Other Notes Payable [Member] Long-term Debt, Type [Axis] Long-term Debt, Type [Axis] Long-term Debt, Type [Domain] Long-term Debt, Type [Domain] Notes payable to banks Notes Payable to Banks [Member] Notes payable Notes Payable, Other Payables [Member] Credit Facility [Axis] Credit Facility [Axis] Credit Facility [Domain] Credit Facility [Domain] Revolving credit facility Revolving Credit Facility [Member] Debt Instrument [Line Items] Debt Instrument [Line Items] Notes payable, total Less: Notes payable, current Notes payable, long term Notes Payable Long-term Debt [Text Block] Income Statement [Abstract] Statement [Table] Statement [Table] Statement [Line Items] Statement [Line Items] Revenues: Revenues [Abstract] Total operating revenues Operating expenses: Operating Expenses [Abstract] Cost of restaurant revenue Cost of Goods and Services Sold Personnel costs Labor and Related Expense Other operating expenses Other Cost and Expense, Operating Goodwill impairment Total operating expenses Costs and Expenses Operating loss Operating Income (Loss) Other income (expense): Nonoperating Income (Expense) [Abstract] Interest, investment and other income Investment Income, Interest and Dividend Total other income Nonoperating Income (Expense) Earnings (loss) before income taxes and equity in losses of unconsolidated affiliates Income tax expense (benefit) Equity in losses of unconsolidated affiliates Net losses from discontinued operations, net of tax - see Note L Income (Loss) from Discontinued Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest Net earnings (loss) Less: Net loss attributable to non-controlling interests Net Income (Loss) Attributable to Noncontrolling Interest Net earnings (loss) attributable to Cannae Holdings, Inc. common shareholders Net Income (Loss) Attributable to Parent Amounts attributable to Cannae Holdings, Inc. common shareholders Income Amounts Attributable to Parent, Disclosures [Abstract] Net earnings (loss) from continuing operations attributable to Cannae Holdings, Inc. common shareholders Income (Loss) from Continuing Operations, Net of Tax, Attributable to Parent Net loss from discontinued operations attributable to Cannae Holdings, Inc. common shareholders Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Parent Earnings per share Earnings Per Share [Abstract] Basic Earnings Per Share, Basic [Abstract] Net earnings (loss) per share from continuing operations (in usd per share) Income (Loss) from Continuing Operations, Per Basic Share Net loss per share from discontinued operations (in usd per share) Discontinued Operation, Income (Loss) from Discontinued Operation, Net of Tax, Per Basic Share Net earnings (loss) per share (in usd per share) Earnings Per Share, Basic Diluted Earnings Per Share, Diluted [Abstract] Net earnings (loss) per share from continuing operations (in usd per share) Income (Loss) from Continuing Operations, Per Diluted Share Net loss per share from discontinued operations (in usd per share) Discontinued Operation, Income (Loss) from Discontinued Operation, Net of Tax, Per Diluted Share Net earnings (loss) per share (in usd per share) Earnings Per Share, Diluted Weighted Average Shares Outstanding Weighted Average Number of Shares Outstanding, Diluted [Abstract] Weighted average shares outstanding Cannae Holdings common stock, basic basis (in shares) Weighted Average Number of Shares Outstanding, Basic Weighted average shares outstanding Cannae Holdings common stock, diluted basis (in shares) Weighted Average Number of Shares Outstanding, Diluted Line of Credit Facility [Table] Line of Credit Facility [Table] 99 Restaurants Credit Facility 99 Term Loan 99 DLOC Loan Margin Loan Agreement Brasada Interstate Credit Agreement Brasada Credit Agreement, Note C Brasada Credit Agreement, Note C [Member] Brasada Credit Agreement, Note C [Member] NV Brasada FNF NV Brasada, LLC [Member] FNF NV Brasada, LLC [Member] Revolver Note Line of Credit Loan Line of Credit [Member] Acquisition Loan Notes Payable To Banks, Acquisition Loan [Member] Notes Payable To Banks, Acquisition Loan [Member] Development Loan Notes Payable To Banks, Development Loan [Member] Notes Payable To Banks, Development Loan [Member] Acquisition Loan, A Note Notes Payable To Banks, Acquisition Loan, A Note [Member] Notes Payable To Banks, Acquisition Loan, A Note [Member] Acquisition Loan, B Note Notes Payable To Banks, Acquisition Loan, B Note [Member] Notes Payable To Banks, Acquisition Loan, B Note [Member] Variable Rate [Axis] Variable Rate [Axis] Variable Rate [Domain] Variable Rate [Domain] Base Rate Base Rate [Member] LIBOR London Interbank Offered Rate (LIBOR) [Member] Line of Credit Facility [Line Items] Line of Credit Facility [Line Items] Aggregate borrowing capacity Line of Credit Facility, Maximum Borrowing Capacity Notes, face amounts Debt Instrument, Face Amount Interest rate basis Debt Instrument, Basis Spread on Variable Rate Interest rate Debt Instrument, Interest Rate, Stated Percentage Amount available to be drawn Line of Credit Facility, Remaining Borrowing Capacity Shares pledged as collateral (in shares) Debt Instrument, Shares, Pledged As Collateral Debt Instrument, Shares, Pledged As Collateral Shares pledged as collateral, shares released (in shares) Debt Instrument, Shares Pledged As Collateral, Shares Released Debt Instrument, Shares Pledged As Collateral, Shares Released Repayment of debt Repayments of Long-term Debt Additional line of credit Variable rate interest Debt Instrument, Interest Rate, Effective Percentage Maximum borrowing increment Line Of Credit Facility, Maximum Borrowing Increment Line Of Credit Facility, Maximum Borrowing Increment Anniversary term Debt Instrument, Term Term of automatic extension Debt Instrument, Term Of Automatic Extension Debt Instrument, Term Of Automatic Extension Restricted cash Restricted Cash Future Undiscounted Payments Under Operating Lease Arrangements Under ASC Topic 842 Lessee, Operating Lease, Liability, Maturity [Table Text Block] Statement of Cash Flows [Abstract] Investments Excluding Dun & Bradstreet Investments Excluding Dun & Bradstreet [Member] Investments Excluding Dun & Bradstreet [Member] Cash flows from operating activities: Net Cash Provided by (Used in) Operating Activities [Abstract] Net earnings (loss) Adjustments to reconcile net earnings (loss) to net cash (used in) provided by operating activities: Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Depreciation and amortization Depreciation, Depletion and Amortization Equity in losses of unconsolidated affiliates Distributions from investments in unconsolidated affiliates Proceeds from Equity Method Investment, Distribution Realized and other gains and losses and asset impairments, net Gain (Loss) on Sale of Assets and Asset Impairment Charges Lease asset amortization Amortization of Leased Asset Stock-based compensation cost Share-based Payment Arrangement, Noncash Expense Changes in assets and liabilities, net of effects from acquisitions: Increase (Decrease) in Operating Capital [Abstract] Net decrease in trade receivables Increase (Decrease) in Accounts Receivable Net increase in inventory, prepaid expenses and other assets Increase (Decrease) In Inventories, Prepaid Expense And Other Assets Increase (Decrease) In Inventories, Prepaid Expense And Other Assets Net decrease in lease liabilities Increase (Decrease) In Lease Liabilities Increase (Decrease) In Lease Liabilities Net decrease (increase) in accounts payable, accrued liabilities, deferred revenue and other Increase (Decrease) In Accounts Payable, Accrued Liabilities, Contract Liabilities, And Other Operating Liabilities Increase (Decrease) In Accounts Payable, Accrued Liabilities, Contract Liabilities, And Other Operating Liabilities Net change in income taxes Increase (Decrease) in Income Taxes Payable Net cash (used in) provided by operating activities Net Cash Provided by (Used in) Operating Activities Cash flows from investing activities: Net Cash Provided by (Used in) Investing Activities [Abstract] Proceeds from sale of investment securities and investments in unconsolidated affiliates Proceeds from Sale of Marketable Securities And Other Investments Proceeds from Sale of Marketable Securities And Other Investments Proceeds from partial sale of Ceridian shares - see Note A Proceeds from Sale of Equity Method Investments Additions to property and equipment and other intangible assets Payments to Acquire Productive Assets Additions to notes receivable Payments to Acquire Notes Receivable Proceeds from sales of property and equipment Proceeds from Sale of Property, Plant, and Equipment Investments in Dun & Bradstreet, net of capitalized syndication fees and other unconsolidated affilates Cash deconsolidated through the Blue Ribbon Reorganization - see Note A Cash Deconsolidated From Reorganization Cash Deconsolidated From Reorganization Distributions from investments in unconsolidated affiliates Proceeds from Equity Method Investment, Distribution, Return of Capital Net proceeds from sales and maturities of short-term investment securities Payments for (Proceeds from) Short-term Investments Net cash provided by (used in) investing activities Net Cash Provided by (Used in) Investing Activities Cash flows from financing activities: Net Cash Provided by (Used in) Financing Activities [Abstract] Borrowings Proceeds from Issuance of Long-term Debt Debt service payments Subsidiary distributions paid to noncontrolling interest shareholders Payments of Ordinary Dividends, Noncontrolling Interest Sale of noncontrolling interest in consolidated subsidiary Proceeds from Noncontrolling Interests Treasury stock repurchases Payments for Repurchase of Common Stock Proceeds from Restaurant Group sale and leaseback of corporate office, net of issuance costs Proceeds From Sale Of Property Plant And Equipment, Leaseback, Finance Lease, Financing Activity Proceeds From Sale Of Property Plant And Equipment, Leaseback, Finance Lease, Financing Activity Net cash (used in) provided by financing activities Net Cash Provided by (Used in) Financing Activities Net decrease in cash and cash equivalents Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect Cash and cash equivalents at beginning of period Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents Cash and cash equivalents at end of period Commitments and Contingencies Commitments and Contingencies Disclosure [Text Block] Schedule of Supplemental Cash Flow information Schedule of Cash Flow, Supplemental Disclosures [Table Text Block] Disposal Groups, Including Discontinued Operations [Table] Disposal Groups, Including Discontinued Operations [Table] Coding Solutions Coding Solutions [Member] Coding Solutions [Member] Disposal Group Name [Axis] Disposal Group Name [Axis] Disposal Group Name [Domain] Disposal Group Name [Domain] T-System Holdings, Inc. T-System Holdings, Inc. [Member] T-System Holdings, Inc. [Member] Disposal Group Classification [Axis] Disposal Group Classification [Axis] Disposal Group Classification [Domain] Disposal Group Classification [Domain] Discontinued Operations, Held-for-sale Discontinued Operations, Held-for-sale [Member] Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] Ownership interest after sale (as a percent) Discontinued Operation, Equity Method Investment Retained after Disposal, Ownership Interest after Disposal Purchase Obligations Recorded Unconditional Purchase Obligations [Table Text Block] Schedule of Variable Interest Entities Schedule of Variable Interest Entities [Table Text Block] 2020 (remaining) Lessee, Operating Lease, Liability, Payments, Remainder of Fiscal Year 2021 Lessee, Operating Lease, Liability, Payments, Due Year Two 2022 Lessee, Operating Lease, Liability, Payments, Due Year Three 2023 Lessee, Operating Lease, Liability, Payments, Due Year Four 2024 Lessee, Operating Lease, Liability, Payments, Due Year Five Thereafter Lessee, Operating Lease, Liability, Payments, Due after Year Five Total lease payments, undiscounted Lessee, Operating Lease, Liability, Payments, Due Less: discount Lessee, Operating Lease, Liability, Undiscounted Excess Amount Total operating lease liability as of March 31, 2020, at present value Operating Lease, Liability Less: operating lease liability as of March 31, 2020, current Operating lease liability as of March 31, 2020, long term Condensed Financial Statements [Table] Condensed Financial Statements [Table] Restatement [Axis] Restatement [Axis] Restatement [Domain] Restatement [Domain] As Previously Reported Previously Reported [Member] Difference Restatement Adjustment [Member] Condensed Financial Statements, Captions [Line Items] Condensed Financial Statements, Captions [Line Items] Condensed Consolidated Statements of Operations Income tax benefit Income Tax Expense (Benefit), Continuing Operations, Discontinued Operations Net earnings (loss) Net earnings (loss) attributable to Cannae Holdings Basic Basic earnings (loss) per share attributable to Cannae Holdings common shareholders (in usd per share) Diluted Diluted earnings (loss) per share attributable to Cannae Holdings common shareholders (in usd per share) Condensed Consolidated Statements of Comprehensive Earnings Unrealized gain relating to investments in unconsolidated affiliates Unrealized Gain (Loss) on Investments Comprehensive earnings (loss) attributable to Cannae Holdings, Inc. Statement of Stockholders' Equity [Abstract] Consolidated Entity Consolidated Entity Excluding Variable Interest Entities (VIE) [Member] Equity Components [Axis] Equity Components [Axis] Equity Component [Domain] Equity Component [Domain] Common Stock Common Stock [Member] Additional Paid-in Capital Additional Paid-in Capital [Member] Retained Earnings Retained Earnings [Member] Accumulated Other Comp (Loss) Earnings AOCI Attributable to Parent [Member] Treasury Stock Treasury Stock [Member] Non-controlling Interests Noncontrolling Interest [Member] Increase (Decrease) in Stockholders' Equity [Roll Forward] Beginning balance (in shares) Shares, Outstanding Beginning balance Adjustment for cumulative effect of adoption of accounting standard Cumulative Effect of New Accounting Principle in Period of Adoption Restaurant Group reorganization and deconsolidation of Blue Ribbon Stockholders' Equity, Increase (Decrease) From Reorganization And Deconsolidation Of Subsidiary Stockholders' Equity, Increase (Decrease) From Reorganization And Deconsolidation Of Subsidiary Other comprehensive earnings — unrealized gain (loss) on investments and other financial instruments, net of tax Other comprehensive earnings — unrealized earnings (losses) on investments in unconsolidated affiliates, net of tax Reclassification adjustments for unrealized gains and losses on unconsolidated affiliates, net of tax, included in net earnings Dun & Bradstreet equity issuance costs Adjustments to Additional Paid in Capital, Stock Issued, Issuance Costs Sale of noncontrolling interest in consolidated subsidiary Noncontrolling Interest, Increase from Sale of Parent Equity Interest Treasury stock repurchases (in shares) Treasury Stock, Shares, Acquired Treasury stock repurchases Treasury Stock, Value, Acquired, Cost Method Stock-based compensation APIC, Share-based Payment Arrangement, Increase for Cost Recognition Contribution of CSA services from FNF Stock Issued During Period, Value, Issued for Services Subsidiary dividends paid to noncontrolling interests Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders Ending balance (in shares) Ending balance 2020 (remaining) Long-term Debt, Maturities, Repayments of Principal, Remainder of Fiscal Year 2021 Long-term Debt, Maturities, Repayments of Principal in Year Two 2022 Long-term Debt, Maturities, Repayments of Principal in Year Three 2023 Long-term Debt, Maturities, Repayments of Principal in Year Four 2024 Long-term Debt, Maturities, Repayments of Principal in Year Five Thereafter Long-term Debt, Maturities, Repayments of Principal after Year Five Total Long Term Debt Long-term Debt, Gross Reconciliation of Operations Disposal Groups, Including Discontinued Operations [Table Text Block] Revenues: Disposal Group, Including Discontinued Operation, Income Statement Disclosures [Abstract] Other operating revenue Disposal Group, Including Discontinued Operation, Other Operating Revenue Disposal Group, Including Discontinued Operation, Other Operating Revenue Total operating revenues Disposal Group, Including Discontinued Operation, Revenue Operating expenses: Disposal Group, Including Discontinued Operation, Operating Expense [Abstract] Disposal Group, Including Discontinued Operation, Operating Expense [Abstract] Personnel costs Disposal Group, Including Discontinued Operation, Labor And Related Expense Disposal Group, Including Discontinued Operation, Labor And Related Expense Depreciation and amortization Disposal Group, Including Discontinued Operation, Depreciation and Amortization Other operating expenses Disposal Group, Including Discontinued Operation, Other Operating Expense Disposal Group, Including Discontinued Operation, Other Operating Expense Total operating expenses Disposal Group, Including Discontinued Operation, Operating Expense Operating loss Disposal Group, Including Discontinued Operation, Operating Income (Loss) Loss from discontinued operations before income taxes Discontinued Operation, Income (Loss) from Discontinued Operation, before Income Tax Income tax benefit Discontinued Operation, Tax Effect of Discontinued Operation Loss from discontinued operations Income tax benefit Effective tax rate Effective Income Tax Rate Reconciliation, Percent Change in deferred taxes Increase (Decrease) in Deferred Income Taxes Other Other Investments In Unconsolidated Affiliates [Member] Other Investments In Unconsolidated Affiliates [Member] Equity securities, FV-NI, ownership percentage Equity Securities, FV-NI, Ownership Percentage Equity Securities, FV-NI, Ownership Percentage Payments to acquire equity method investments Investments Investments In Available-For-Sale Debt Securities And Equity Method Investments [Text Block] Investments In Available-For-Sale Debt Securities And Equity Method Investments [Text Block] Summary of Change in Accounting Principle Schedule of New Accounting Pronouncements and Changes in Accounting Principles [Table Text Block] Disaggregation of Revenue [Table] Disaggregation of Revenue [Table] Total other operating revenue Restaurant sales Bakery sales Bakery Sales [Member] Bakery Sales [Member] Franchise and other Franchise And Other [Member] Franchise And Other [Member] Real estate and resort Real Estate And Resort [Member] Real Estate And Resort [Member] Other Other Products And Services [Member] Other Products And Services [Member] Disaggregation of Revenue [Line Items] Disaggregation of Revenue [Line Items] Total operating revenues