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Summary of Significant Accounting Policies (Narrative) (Detail) - USD ($) $ in Thousands | 12 Months Ended |  |  |  |  |
--- | --- | --- | --- | --- | --- | ---
Dec. 31, 2020 | Dec. 31, 2018 | Jan. 01, 2020 | Dec. 31, 2019 | Jan. 01, 2019 | Jan. 01, 2018 | Dec. 31, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |  |  |  |  |  |
Cash on hand or on deposit required | $ 42,000 |  |  | $ 918,000 |  |  |
Cash collateral on deposit | 74,000 |  |  | 37,500 |  |  |
Foreclosed assets | 850 |  |  | 1,100 |  |  |
Cumulative effect of accounting change |  | $ (14,672) |  | (29,252) |  |  | $ (2,285)
Operating Lease, Right-of-Use Asset | $ 292,087 |  |  | 297,736 | $ 170,500 |  |
Minimum [Member] |  |  |  |  |  |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |  |  |  |  |  |
Range of change in fair value of derivative hedging instrument to be considered highly effective | 80.00% |  |  |  |  |  |
Maximum [Member] |  |  |  |  |  |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |  |  |  |  |  |
Range of change in fair value of derivative hedging instrument to be considered highly effective | 125.00% |  |  |  |  |  |
Other Liabilities [Member] |  |  |  |  |  |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |  |  |  |  |  |
Operating lease, liability | $ 323,044 |  |  | 323,700 | 174,400 |  |
Retained Earnings [Member] |  |  |  |  |  |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |  |  |  |  |  |
Cumulative effect of accounting change |  | (14,672) | $ (29,300) | $ (29,252) | $ (14,700) | $ (2,300) | $ (2,285)
Reclassification of certain income tax effects related to the change in the U.S. statutory federal income tax rate under the Tax Cuts and Jobs Act |  | (9,535) |  |  |  |  |
Accumulated Other Comprehensive Income (Loss), Net of Tax [Member] |  |  |  |  |  |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |  |  |  |  |  |
Reclassification of certain income tax effects related to the change in the U.S. statutory federal income tax rate under the Tax Cuts and Jobs Act |  | $ 9,535 |  |  |  |  |

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