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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 | 3 Months Ended | 6 Months Ended |  |  |  |
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Jun. 30, 2020 | Jun. 30, 2019 | Jun. 30, 2020 | Jun. 30, 2019 | Mar. 31, 2020 | Dec. 31, 2019 | Mar. 31, 2019 | Dec. 31, 2018
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 | $ 5,848,000 | $ 7,080,000 | $ 5,848,000 | $ 7,080,000 | $ 5,884,000 | $ 6,207,000 | $ 7,139,000 | $ 6,930,000
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Gain Loss Included In Earnings | 72,000 | 193,000 | 201,000 | 353,000 |  |  |  |
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Gain Loss Included In Other Comprehensive Income Loss | (22,000) | (163,000) | (398,000) | (28,000) |  |  |  |
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Purchases |  |  | 0 | 0 |  |  |  |
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Issues |  |  | 0 | 0 |  |  |  |
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Sales |  |  | 0 | 0 |  |  |  |
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Settlements | (86,000) | (89,000) | (162,000) | (176,000) |  |  |  |
Fair Value Asset Or Liability Measured On Recurring Basis Change In Unrealized Gains Losses Still Held |  |  | 201,000 | 352,000 |  |  |  |
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 | 66,000 | 74,000 | 66,000 | 74,000 | 66,000 | 72,000 | 72,000 | 72,000
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Gain Loss Included In Earnings | 0 | 0 | 1,000 | 1,000 |  |  |  |
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Gain Loss Included In Other Comprehensive Income Loss | 0 | 2,000 | (6,000) | 2,000 |  |  |  |
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Purchases |  |  | 0 | 0 |  |  |  |
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Issues |  |  | 0 | 0 |  |  |  |
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Sales |  |  | 0 | 0 |  |  |  |
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Settlements | 0 | 0 | (1,000) | (1,000) |  |  |  |
Fair Value Asset Or Liability Measured On Recurring Basis Change In Unrealized Gains Losses Still Held |  |  | 0 | 0 |  |  |  |
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 | 2,000 | 4,000 | 2,000 | 4,000 | 3,000 | 3,000 | 4,000 | 5,000
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Gain Loss Included In Earnings | 0 | 0 | (1,000) | (1,000) |  |  |  |
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Gain Loss Included In Other Comprehensive Income Loss |  |  | 0 | 0 |  |  |  |
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Purchases |  |  | 0 | 0 |  |  |  |
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Issues |  |  | 0 | 0 |  |  |  |
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Sales |  |  | 0 | 0 |  |  |  |
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Settlements |  |  | 0 | 0 |  |  |  |
Fair Value Asset Or Liability Measured On Recurring Basis Change In Unrealized Gains Losses Still Held |  |  | (1,000) | (1,000) |  |  |  |
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 | 86,000 | 62,000 | 86,000 | 62,000 |  | $ 66,000 |  |
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Gain Loss Included In Earnings |  |  | 23,000 |  |  |  |  |
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Gain Loss Included In Other Comprehensive Income Loss |  |  | 0 |  |  |  |  |
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Purchases |  |  | 0 |  |  |  |  |
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Issues |  |  | 0 |  |  |  |  |
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Sales |  |  | 0 |  |  |  |  |
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Settlements |  |  | (3,000) |  |  |  |  |
Fair Value Asset Or Liability Measured On Recurring Basis Change In Unrealized Gains Losses Still Held |  |  | 23,000 |  |  |  |  |
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 |  | 4,289,000 |  | 4,289,000 |  |  |  |
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 |  | (231,000) |  | (231,000) |  |  |  |
Derivative Financial Instruments, Liabilities [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 |  |  |  |  |  |  |  | $ 46,000
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Gain Loss Included In Earnings |  |  |  | 19,000 |  |  |  |
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Gain Loss Included In Other Comprehensive Income Loss |  |  |  | 0 |  |  |  |
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Purchases |  |  |  | 0 |  |  |  |
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Issues |  |  |  | 0 |  |  |  |
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Sales |  |  |  | 0 |  |  |  |
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Settlements |  |  |  | (2,000) |  |  |  |
Fair Value Asset Or Liability Measured On Recurring Basis Change In Unrealized Gains Losses Still Held |  |  |  | 18,000 |  |  |  |
Derivative Financial Instruments, Liabilities [Member] | 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 | 86,000 | 62,000 | $ 86,000 | 62,000 | $ 77,000 |  | $ 53,000 |
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Gain Loss Included In Earnings | 11,000 | 10,000 |  |  |  |  |  |
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Settlements | $ (2,000) | (1,000) |  |  |  |  |  |
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 |  | $ 2,882,000 |  | $ 2,882,000 |  |  |  |
Variable Interest Entity [Member] |  |  |  |  |  |  |  |
Fair Value Inputs, Liabilities, Quantitative Information [Line Items] (Deprecated 2018-01-31) |  |  |  |  |  |  |  |
Estimated Future Premium Payments Minimum Discounted Rate | 2.10% |  | 2.10% |  |  |  |  |
Estimated Future Premium Payments Maximum Discounted Rate | 5.80% |  | 5.80% |  |  |  |  |

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- Definition Estimated Future Premium Payments Minimum Discounted Rate + 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 measurement with unobservable inputs reconciliation recurring basis asset or liability. + References No definition available. + Details
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- Definition Amount of gain or loss included in earnings arising from financial instruments measured on a recurring basis using unobservable inputs. + References No definition available. + Details
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- Definition Amount of gain or loss included in other comprehensive income arising from financial instruments measured on a recurring basis using unobservable inputs. + References No definition available. + Details
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- Definition Amount of issuances related to financial instruments measured on a recurring basis using unobservable inputs. + References No definition available. + Details
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- Definition Amount of purchases of financial instruments measured on a recurring basis using unobservable inputs. + References No definition available. + Details
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- Definition Amount of sales of financial instruments measured on a recurring basis using unobservable inputs. + References No definition available. + Details
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- Definition Amount of settlements related to financial instruments measured on a recurring basis using unobservable inputs. + 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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