Investment Securities (Summary Of Investment Securities) (Detail) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Debt Securities, Held-to-maturity, Fair Value to Amortized Cost [Abstract]
Amortized Cost	$ 6,564,879	$ 6,198,339
Unrealized Gains	2,770	138,254
Unrealized Losses	(806,196)	(55,657)
Fair Value	5,761,453	6,280,936
Debt Securities, Held-to-maturity, Allowance for Credit Loss	182	214	$ 299	$ 0
Debt Securities, Held-to-maturity, Current	6,564,697	6,198,125
Interest Receivable	226,300	50,700
Debt Securities, Available-for-sale [Abstract]
Unrealized Gains	31	41,499
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	864,489	34,342
Pledged Financial Instruments, Not Separately Reported, Debt Securities Held-to-Maturity	1,857,512	3,077,256
Pledged Financial Instruments, Not Separately Reported, Debt Securities Available-for-sale or Held-for-investment	3,768,173	1,780,164
Debt Securities, Available-for-Sale, Amortized Cost, Excluding Accrued Interest, before Allowance for Credit Loss	8,757,155	4,227,697
Fair Value	7,892,697	4,234,854
Held-to-maturity Securities [Member]
Debt Securities, Held-to-maturity, Fair Value to Amortized Cost [Abstract]
Interest Receivable	24,200	21,200
Available-for-sale Securities
Debt Securities, Held-to-maturity, Fair Value to Amortized Cost [Abstract]
Interest Receivable	36,900	7,500
Agency CMO
Debt Securities, Held-to-maturity, Fair Value to Amortized Cost [Abstract]
Amortized Cost	28,358	42,405
Unrealized Gains	0	655
Unrealized Losses	(2,060)	(25)
Fair Value	26,298	43,035
Debt Securities, Held-to-maturity, Allowance for Credit Loss	0	0
Debt Securities, Held-to-maturity, Current	28,358	42,405
Debt Securities, Available-for-sale [Abstract]
Unrealized Gains	0	2,326
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	5,019	51
Debt Securities, Available-for-Sale, Amortized Cost, Excluding Accrued Interest, before Allowance for Credit Loss	64,984	88,109
Fair Value	59,965	90,384
Agency MBS
Debt Securities, Held-to-maturity, Fair Value to Amortized Cost [Abstract]
Amortized Cost	2,626,114	2,901,593
Unrealized Gains	827	71,444
Unrealized Losses	(339,592)	(11,788)
Fair Value	2,287,349	2,961,249
Debt Securities, Held-to-maturity, Allowance for Credit Loss	0	0
Debt Securities, Held-to-maturity, Current	2,626,114	2,901,593
Debt Securities, Available-for-sale [Abstract]
Unrealized Gains	26	36,130
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	303,339	11,020
Debt Securities, Available-for-Sale, Amortized Cost, Excluding Accrued Interest, before Allowance for Credit Loss	2,461,337	1,568,293
Fair Value	2,158,024	1,593,403
Agency commercial mortgage-backed securities (agency CMBS) [Member]
Debt Securities, Held-to-maturity, Fair Value to Amortized Cost [Abstract]
Amortized Cost	2,831,949	2,378,475
Unrealized Gains	845	11,202
Unrealized Losses	(407,648)	(43,844)
Fair Value	2,425,146	2,345,833
Debt Securities, Held-to-maturity, Allowance for Credit Loss	0	0
Debt Securities, Held-to-maturity, Current	2,831,949	2,378,475
Debt Securities, Available-for-sale [Abstract]
Unrealized Gains	0	2,537
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	258,114	18,544
Debt Securities, Available-for-Sale, Amortized Cost, Excluding Accrued Interest, before Allowance for Credit Loss	1,664,600	1,248,548
Fair Value	1,406,486	1,232,541
CMBS
Debt Securities, Held-to-maturity, Fair Value to Amortized Cost [Abstract]
Amortized Cost	149,613	169,948
Unrealized Gains	0	3,381
Unrealized Losses	(9,713)	0
Fair Value	139,900	173,329
Debt Securities, Held-to-maturity, Allowance for Credit Loss	0	0
Debt Securities, Held-to-maturity, Current	149,613	169,948
Debt Securities, Available-for-sale [Abstract]
Unrealized Gains	0	506
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	32,948	1,883
Debt Securities, Available-for-Sale, Amortized Cost, Excluding Accrued Interest, before Allowance for Credit Loss	929,588	887,640
Fair Value	896,640	886,263
CLO
Debt Securities, Available-for-sale [Abstract]
Unrealized Gains	0	0
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	1	13
Debt Securities, Available-for-Sale, Amortized Cost, Excluding Accrued Interest, before Allowance for Credit Loss	2,108	21,860
Fair Value	2,107	21,847
Corporate debt
Debt Securities, Available-for-sale [Abstract]
Unrealized Gains	0	0
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	91,587	1,133
Debt Securities, Available-for-Sale, Amortized Cost, Excluding Accrued Interest, before Allowance for Credit Loss	795,999	14,583
Fair Value	704,412	13,450
Municipal Bonds [Member]
Debt Securities, Held-to-maturity, Fair Value to Amortized Cost [Abstract]
Amortized Cost	928,845	705,918
Unrealized Gains	1,098	51,572
Unrealized Losses	(47,183)	0
Fair Value	882,760	757,490
Debt Securities, Held-to-maturity, Allowance for Credit Loss	182	214
Debt Securities, Held-to-maturity, Current	928,663	705,704
U.S. Treasury notes
Debt Securities, Available-for-sale [Abstract]
Unrealized Gains	0	0
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	38,928	1,698
Debt Securities, Available-for-Sale, Amortized Cost, Excluding Accrued Interest, before Allowance for Credit Loss	755,968	398,664
Fair Value	717,040	$ 396,966
Government agency debentures
Debt Securities, Available-for-sale [Abstract]
Unrealized Gains	0
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	43,644
Debt Securities, Available-for-Sale, Amortized Cost, Excluding Accrued Interest, before Allowance for Credit Loss	302,018
Fair Value	258,374
Municipal bonds and notes
Debt Securities, Available-for-sale [Abstract]
Unrealized Gains	5
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	85,913
Debt Securities, Available-for-Sale, Amortized Cost, Excluding Accrued Interest, before Allowance for Credit Loss	1,719,110
Fair Value	1,633,202
Private label MBS
Debt Securities, Available-for-sale [Abstract]
Unrealized Gains	0
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	4,646
Debt Securities, Available-for-Sale, Amortized Cost, Excluding Accrued Interest, before Allowance for Credit Loss	48,895
Fair Value	44,249
Other
Debt Securities, Available-for-sale [Abstract]
Unrealized Gains	0
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	350
Debt Securities, Available-for-Sale, Amortized Cost, Excluding Accrued Interest, before Allowance for Credit Loss	12,548
Fair Value	$ 12,198