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Fair Value Measurements - Information about Valuation Inputs for Variable Interest Entity Assets and Liabilities Classified as Level 3 (Detail) - USD ($) $ in Thousands | 12 Months Ended
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Dec. 31, 2018 | Dec. 31, 2017 | Dec. 31, 2016
Fair Value Inputs, Liabilities, Quantitative Information [Line Items] (Deprecated 2018-01-31) |  |  |
Estimated Future Premium Payments Weighted Average Discounted Rate | 2.70% | 2.50% |
Asset-backed Securities [Member] |  |  |
Fair Value Inputs, Liabilities, Quantitative Information [Line Items] (Deprecated 2018-01-31) |  |  |
Fair Value Inputs Coupon Rate | 5.97% | 5.97% |
Fair Value Inputs Maturity | 16 years 3 months 15 days | 17 years 9 days |
Fair Value Inputs Yield | 12.00% | 12.00% |
Fair Value, Inputs, Level 3 [Member] |  |  |
Fair Value Inputs, Liabilities, Quantitative Information [Line Items] (Deprecated 2018-01-31) |  |  |
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Deconsolidation Of Vies | $ 3,709,113 |  |
Fair Value, Inputs, Level 3 [Member] | Investments [Member] |  |  |
Fair Value Inputs, Liabilities, Quantitative Information [Line Items] (Deprecated 2018-01-31) |  |  |
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Deconsolidation Of Vies | 0 |  |
Fair Value, Inputs, Level 3 [Member] | European ABS Transactions [Member] |  |  |
Fair Value Inputs, Liabilities, Quantitative Information [Line Items] (Deprecated 2018-01-31) |  |  |
Fair Value Of Consolidated Variable Interest Entity Debt Obligations Valued Using Unobservable Inputs By Asset Class | 217,092 | $ 2,757,688 |
Fair Value, Inputs, Level 3 [Member] | Other Assets [Member] |  |  |
Fair Value Inputs, Liabilities, Quantitative Information [Line Items] (Deprecated 2018-01-31) |  |  |
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Deconsolidation Of Vies | 0 |  |
Fair Value, Inputs, Level 3 [Member] | Derivative Financial Instruments, Liabilities [Member] |  |  |
Fair Value Inputs, Liabilities, Quantitative Information [Line Items] (Deprecated 2018-01-31) |  |  |
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Deconsolidation Of Vies | 0 |  |
Loan Origination Commitments [Member] | Fair Value, Inputs, Level 3 [Member] |  |  |
Fair Value Inputs, Liabilities, Quantitative Information [Line Items] (Deprecated 2018-01-31) |  |  |
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Deconsolidation Of Vies | 5,946,465 |  |
Long-term Debt [Member] | Fair Value, Inputs, Level 3 [Member] |  |  |
Fair Value Inputs, Liabilities, Quantitative Information [Line Items] (Deprecated 2018-01-31) |  |  |
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Deconsolidation Of Vies | (2,237,352) |  |
Investment Contracts [Member] | Fair Value, Inputs, Level 3 [Member] |  |  |
Fair Value Inputs, Liabilities, Quantitative Information [Line Items] (Deprecated 2018-01-31) |  |  |
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Deconsolidation Of Vies | $ 0 |  |
Variable Interest Entity, Primary Beneficiary [Member] |  |  |
Fair Value Inputs, Liabilities, Quantitative Information [Line Items] (Deprecated 2018-01-31) |  |  |
Fair Value Asset Or Liability Measured On Recurring Basis Change In Unrealized Gains Losses Still Held |  |  | $ 833,023
Estimated Future Premium Payments Weighted Average Discounted Rate | 3.10% | 3.10% |
Variable Interest Entity, Primary Beneficiary [Member] | European ABS Transactions [Member] |  |  |
Fair Value Inputs, Liabilities, Quantitative Information [Line Items] (Deprecated 2018-01-31) |  |  |
Fair Value Inputs Coupon Rate | 2.20% | 0.40% |
Fair Value Inputs Maturity | 18 years 11 months 6 days | 15 years 3 months 11 days |
Fair Value Inputs Yield | 3.18% | 4.82% |

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- Definition Weighted average discounted rate of estimated future premium payments to be paid by the VIEs. + References No definition available. + Details
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- Definition The amount of gains or losses included in earnings attributable to unrealized gains or losses on financial instruments measured on a recurring basis using unobservable inputs that are still held at the reporting date. + References No definition available. + Details
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- Definition Fair value inputs coupon rate. + References No definition available. + Details
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- Definition Fair value inputs maturity. + References No definition available. + Details
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- Definition Fair value inputs yield. + References No definition available. + Details
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- Definition Fair value of financial instruments measured on a recurring basis using unobservable inputs removed as a result of the deconsolidation of variable interest entities. + References No definition available. + Details
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- Definition Fair Value of consolidated VIE debt obligations valued using unobservable inputs by asset class + References No definition available. + Details
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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
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