Fair Value Measurements (Fair Value Assets And Liabilities Measured On Recurring and Nonrecurring Basis) (Detail) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Financial assets held at fair value:
Investment securities available-for-sale, at fair value	$ 3,304,217	$ 2,925,833
Gross derivative instruments, before netting (1)	343,890	133,158
Loans held for sale (valued under fair value option $29,018 and $35,750)	29,018	35,750
Financial liabilities held at fair value:
Derivative liability	772	7,163
Agency CMO [Member]
Financial assets held at fair value:
Investment securities available-for-sale, at fair value	173,354	185,801
Agency MBS [Member]
Financial assets held at fair value:
Investment securities available-for-sale, at fair value	1,527,270	1,612,164
Agency CMBS [Member]
Financial assets held at fair value:
Investment securities available-for-sale, at fair value	1,051,754	581,552
Non-agency CMBS [Member]
Financial assets held at fair value:
Investment securities available-for-sale, at fair value	455,025	431,871
CLO [Member]
Financial assets held at fair value:
Investment securities available-for-sale, at fair value	84,361	92,205
Corporate debt securities [Member]
Financial assets held at fair value:
Investment securities available-for-sale, at fair value	12,453	22,240
Fair Value, Recurring [Member]
Financial assets held at fair value:
Investment securities available-for-sale, at fair value	3,304,217	2,925,833
Alternative investments (2)	8,238	4,331
Total financial assets held at fair value	3,734,569	3,116,731
Financial liabilities held at fair value:
Derivative liability	18,247	13,813
Fair Value, Recurring [Member] \| Quoted Prices in Active Markets For Identical Assets (Level 1) [Member]
Financial assets held at fair value:
Alternative investments (2)	0	0
Total financial assets held at fair value	4,866	5,108
Financial liabilities held at fair value:
Derivative liability	229	611
Fair Value, Recurring [Member] \| Significant Other Observable Inputs (Level 2) [Member]
Financial assets held at fair value:
Investment securities available-for-sale, at fair value	3,304,217	2,925,833
Alternative investments (2)	0	0
Total financial assets held at fair value	3,721,465	3,107,292
Financial liabilities held at fair value:
Derivative liability	18,018	13,202
Fair Value, Recurring [Member] \| Derivative instruments [Member]
Financial assets held at fair value:
Gross derivative instruments, before netting (1)	388,439	146,037
Fair Value, Recurring [Member] \| Derivative instruments [Member] \| Quoted Prices in Active Markets For Identical Assets (Level 1) [Member]
Financial assets held at fair value:
Gross derivative instruments, before netting (1)	209	328
Fair Value, Recurring [Member] \| Derivative instruments [Member] \| Significant Other Observable Inputs (Level 2) [Member]
Financial assets held at fair value:
Gross derivative instruments, before netting (1)	388,230	145,709
Fair Value, Recurring [Member] \| Investments Held In Rabbi Trust [Member]
Financial assets held at fair value:
Other assets	4,657	4,780
Fair Value, Recurring [Member] \| Investments Held In Rabbi Trust [Member] \| Quoted Prices in Active Markets For Identical Assets (Level 1) [Member]
Financial assets held at fair value:
Other assets	4,657	4,780
Fair Value, Recurring [Member] \| Loan Origination Commitments [Member]
Financial assets held at fair value:
Loans held for sale (valued under fair value option $29,018 and $35,750)	29,018	35,750
Fair Value, Recurring [Member] \| Loan Origination Commitments [Member] \| Quoted Prices in Active Markets For Identical Assets (Level 1) [Member]
Financial assets held at fair value:
Loans held for sale (valued under fair value option $29,018 and $35,750)	0	0
Fair Value, Recurring [Member] \| Loan Origination Commitments [Member] \| Significant Other Observable Inputs (Level 2) [Member]
Financial assets held at fair value:
Loans held for sale (valued under fair value option $29,018 and $35,750)	29,018	35,750
Fair Value, Recurring [Member] \| Agency CMO [Member]
Financial assets held at fair value:
Investment securities available-for-sale, at fair value	173,354	185,801
Fair Value, Recurring [Member] \| Agency CMO [Member] \| Significant Other Observable Inputs (Level 2) [Member]
Financial assets held at fair value:
Investment securities available-for-sale, at fair value	173,354	185,801
Fair Value, Recurring [Member] \| Agency MBS [Member]
Financial assets held at fair value:
Investment securities available-for-sale, at fair value	1,527,270	1,612,164
Fair Value, Recurring [Member] \| Agency MBS [Member] \| Significant Other Observable Inputs (Level 2) [Member]
Financial assets held at fair value:
Investment securities available-for-sale, at fair value	1,527,270	1,612,164
Fair Value, Recurring [Member] \| Agency CMBS [Member]
Financial assets held at fair value:
Investment securities available-for-sale, at fair value	1,051,754	581,552
Fair Value, Recurring [Member] \| Agency CMBS [Member] \| Quoted Prices in Active Markets For Identical Assets (Level 1) [Member]
Financial assets held at fair value:
Investment securities available-for-sale, at fair value	0	0
Fair Value, Recurring [Member] \| Agency CMBS [Member] \| Significant Other Observable Inputs (Level 2) [Member]
Financial assets held at fair value:
Investment securities available-for-sale, at fair value	1,051,754	581,552
Fair Value, Recurring [Member] \| Agency CMBS [Member] \| Significant Unobservable Inputs (Level 3) [Member]
Financial assets held at fair value:
Investment securities available-for-sale, at fair value	0	0
Fair Value, Recurring [Member] \| Non-agency CMBS [Member]
Financial assets held at fair value:
Investment securities available-for-sale, at fair value	455,025	431,871
Fair Value, Recurring [Member] \| Non-agency CMBS [Member] \| Quoted Prices in Active Markets For Identical Assets (Level 1) [Member]
Financial assets held at fair value:
Investment securities available-for-sale, at fair value	0	0
Fair Value, Recurring [Member] \| Non-agency CMBS [Member] \| Significant Other Observable Inputs (Level 2) [Member]
Financial assets held at fair value:
Investment securities available-for-sale, at fair value	455,025	431,871
Fair Value, Recurring [Member] \| Non-agency CMBS [Member] \| Significant Unobservable Inputs (Level 3) [Member]
Financial assets held at fair value:
Investment securities available-for-sale, at fair value	0	0
Fair Value, Recurring [Member] \| CLO [Member]
Financial assets held at fair value:
Investment securities available-for-sale, at fair value	84,361	92,205
Fair Value, Recurring [Member] \| CLO [Member] \| Significant Other Observable Inputs (Level 2) [Member]
Financial assets held at fair value:
Investment securities available-for-sale, at fair value	84,361	92,205
Fair Value, Recurring [Member] \| Corporate debt securities [Member]
Financial assets held at fair value:
Investment securities available-for-sale, at fair value	12,453	22,240
Fair Value, Recurring [Member] \| Corporate debt securities [Member] \| Significant Other Observable Inputs (Level 2) [Member]
Financial assets held at fair value:
Investment securities available-for-sale, at fair value	$ 12,453	$ 22,240

Fair value of investment other than investment in equity security, investment in debt security and equity method investment. Includes, but is not limited to, investment in certain entities that calculate net asset value per share. Example includes, but is not limited to, investment in hedge fund, venture capital fund, private equity fund, and real estate partnership or fund.

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Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Fair value portion of loans held-for-sale including, but not limited to, mortgage loans and finance receivables.

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