Investment Securities (Summary Of Debt Securities Available-for-Sale) (Detail) $ in Thousands	Jun. 30, 2023 USD ($) holding	Dec. 31, 2022 USD ($) holding
Debt Securities, Available-for-sale [Abstract]
Amortized Cost - Total available-for-sale debt securities	$ 8,642,304	$ 8,757,155
Unrealized Gains	58	31
Unrealized Losses	(883,021)	(864,489)
Investment securities available-for-sale, at fair value	7,759,341	7,892,697
Less than 12 months, fair value	688,004	5,417,865
Less than 12 months, unrealized losses	(22,383)	(532,120)
12 months or more, fair value	7,010,350	2,429,126
12 months or more, unrealized losses	$ (860,638)	$ (332,369)
Total, number of holdings | holding	1,245	1,282
Total, fair value	$ 7,698,354	$ 7,846,991
Total, unrealized losses	(883,021)	(864,489)
Amortized Cost
Maturing within 1 year	33,337
After 1 year through 5 years	1,040,297
After 5 through 10 years	1,401,731
After 10 years	6,166,939
Amortized Cost - Total available-for-sale debt securities	8,642,304	8,757,155
Fair Value
Maturing within 1 year	33,164
After 1 year through 5 years	978,096
After 5 through 10 years	1,277,563
After 10 years	5,470,518
Fair Value, Total available-for-sale debt securities	7,759,341	7,892,697
Available-for-sale securities pledged	6,462,973	3,768,173
Debt Securities, Available-for-Sale, Unrealized Loss Position [Line Items]
Less than 12 months, fair value	688,004	5,417,865
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	22,383	532,120
12 months or more, fair value	7,010,350	2,429,126
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ 860,638	$ 332,369
Total, number of holdings | holding	1,245	1,282
Total, fair value	$ 7,698,354	$ 7,846,991
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	883,021	864,489
U.S. Treasury notes
Debt Securities, Available-for-sale [Abstract]
Amortized Cost - Total available-for-sale debt securities	407,555	755,968
Unrealized Gains	0	0
Unrealized Losses	(23,488)	(38,928)
Investment securities available-for-sale, at fair value	384,067	717,040
Less than 12 months, fair value		337,563
Less than 12 months, unrealized losses		(19,167)
12 months or more, fair value	384,067	379,477
12 months or more, unrealized losses	$ (23,488)	$ (19,761)
Total, number of holdings | holding	14	23
Total, fair value	$ 384,067	$ 717,040
Total, unrealized losses	(23,488)	(38,928)
Amortized Cost
Amortized Cost - Total available-for-sale debt securities	407,555	755,968
Fair Value
Fair Value, Total available-for-sale debt securities	384,067	717,040
Debt Securities, Available-for-Sale, Unrealized Loss Position [Line Items]
Less than 12 months, fair value		337,563
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss		19,167
12 months or more, fair value	384,067	379,477
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ 23,488	$ 19,761
Total, number of holdings | holding	14	23
Total, fair value	$ 384,067	$ 717,040
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	23,488	38,928
Government agency debentures
Debt Securities, Available-for-sale [Abstract]
Amortized Cost - Total available-for-sale debt securities	302,115	302,018
Unrealized Gains	0	0
Unrealized Losses	(41,014)	(43,644)
Investment securities available-for-sale, at fair value	261,101	258,374
Less than 12 months, fair value	32,481	258,374
Less than 12 months, unrealized losses	(2,376)	$ (43,644)
12 months or more, fair value	228,620
12 months or more, unrealized losses	$ (38,638)
Total, number of holdings | holding	19	19
Total, fair value	$ 261,101	$ 258,374
Total, unrealized losses	(41,014)	(43,644)
Amortized Cost
Amortized Cost - Total available-for-sale debt securities	302,115	302,018
Fair Value
Fair Value, Total available-for-sale debt securities	261,101	258,374
Debt Securities, Available-for-Sale, Unrealized Loss Position [Line Items]
Less than 12 months, fair value	32,481	258,374
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	2,376	$ 43,644
12 months or more, fair value	228,620
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ 38,638
Total, number of holdings | holding	19	19
Total, fair value	$ 261,101	$ 258,374
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	41,014	43,644
Municipal bonds and notes
Debt Securities, Available-for-sale [Abstract]
Amortized Cost - Total available-for-sale debt securities	1,678,826	1,719,110
Unrealized Gains	5	5
Unrealized Losses	(74,681)	(85,913)
Investment securities available-for-sale, at fair value	1,604,150	1,633,202
Less than 12 months, fair value	30,722	1,616,771
Less than 12 months, unrealized losses	(506)	$ (85,913)
12 months or more, fair value	1,554,918
12 months or more, unrealized losses	$ (74,175)
Total, number of holdings | holding	420	444
Total, fair value	$ 1,585,640	$ 1,616,771
Total, unrealized losses	(74,681)	(85,913)
Amortized Cost
Amortized Cost - Total available-for-sale debt securities	1,678,826	1,719,110
Fair Value
Fair Value, Total available-for-sale debt securities	1,604,150	1,633,202
Debt Securities, Available-for-Sale, Unrealized Loss Position [Line Items]
Less than 12 months, fair value	30,722	1,616,771
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	506	$ 85,913
12 months or more, fair value	1,554,918
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ 74,175
Total, number of holdings | holding	420	444
Total, fair value	$ 1,585,640	$ 1,616,771
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	74,681	85,913
Agency CMO
Debt Securities, Available-for-sale [Abstract]
Amortized Cost - Total available-for-sale debt securities	58,529	64,984
Unrealized Gains	0	0
Unrealized Losses	(5,169)	(5,019)
Investment securities available-for-sale, at fair value	53,360	59,965
Less than 12 months, fair value	7,018	55,693
Less than 12 months, unrealized losses	(349)	(4,640)
12 months or more, fair value	46,342	4,272
12 months or more, unrealized losses	$ (4,820)	$ (379)
Total, number of holdings | holding	37	39
Total, fair value	$ 53,360	$ 59,965
Total, unrealized losses	(5,169)	(5,019)
Amortized Cost
Amortized Cost - Total available-for-sale debt securities	58,529	64,984
Fair Value
Fair Value, Total available-for-sale debt securities	53,360	59,965
Debt Securities, Available-for-Sale, Unrealized Loss Position [Line Items]
Less than 12 months, fair value	7,018	55,693
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	349	4,640
12 months or more, fair value	46,342	4,272
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ 4,820	$ 379
Total, number of holdings | holding	37	39
Total, fair value	$ 53,360	$ 59,965
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	5,169	5,019
Agency MBS
Debt Securities, Available-for-sale [Abstract]
Amortized Cost - Total available-for-sale debt securities	2,476,218	2,461,337
Unrealized Gains	9	26
Unrealized Losses	(291,320)	(303,339)
Investment securities available-for-sale, at fair value	2,184,907	2,158,024
Less than 12 months, fair value	197,989	1,641,544
Less than 12 months, unrealized losses	(4,220)	(206,412)
12 months or more, fair value	1,986,029	515,206
12 months or more, unrealized losses	$ (287,100)	$ (96,927)
Total, number of holdings | holding	465	460
Total, fair value	$ 2,184,018	$ 2,156,750
Total, unrealized losses	(291,320)	(303,339)
Amortized Cost
Amortized Cost - Total available-for-sale debt securities	2,476,218	2,461,337
Fair Value
Fair Value, Total available-for-sale debt securities	2,184,907	2,158,024
Debt Securities, Available-for-Sale, Unrealized Loss Position [Line Items]
Less than 12 months, fair value	197,989	1,641,544
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	4,220	206,412
12 months or more, fair value	1,986,029	515,206
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ 287,100	$ 96,927
Total, number of holdings | holding	465	460
Total, fair value	$ 2,184,018	$ 2,156,750
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	291,320	303,339
Agency CMBS
Debt Securities, Available-for-sale [Abstract]
Amortized Cost - Total available-for-sale debt securities	2,041,431	1,664,600
Unrealized Gains	44	0
Unrealized Losses	(306,553)	(258,114)
Investment securities available-for-sale, at fair value	1,734,922	1,406,486
Less than 12 months, fair value	345,784	485,333
Less than 12 months, unrealized losses	(10,832)	(68,674)
12 months or more, fair value	1,347,550	921,153
12 months or more, unrealized losses	$ (295,721)	$ (189,440)
Total, number of holdings | holding	142	132
Total, fair value	$ 1,693,334	$ 1,406,486
Total, unrealized losses	(306,553)	(258,114)
Amortized Cost
Amortized Cost - Total available-for-sale debt securities	2,041,431	1,664,600
Fair Value
Fair Value, Total available-for-sale debt securities	1,734,922	1,406,486
Debt Securities, Available-for-Sale, Unrealized Loss Position [Line Items]
Less than 12 months, fair value	345,784	485,333
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	10,832	68,674
12 months or more, fair value	1,347,550	921,153
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ 295,721	$ 189,440
Total, number of holdings | holding	142	132
Total, fair value	$ 1,693,334	$ 1,406,486
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	306,553	258,114
CMBS
Debt Securities, Available-for-sale [Abstract]
Amortized Cost - Total available-for-sale debt securities	907,602	929,588
Unrealized Gains	0	0
Unrealized Losses	(31,483)	(32,948)
Investment securities available-for-sale, at fair value	876,119	896,640
Less than 12 months, fair value	48,536	273,150
Less than 12 months, unrealized losses	(1,439)	(8,982)
12 months or more, fair value	827,583	598,490
12 months or more, unrealized losses	$ (30,044)	$ (23,966)
Total, number of holdings | holding	51	52
Total, fair value	$ 876,119	$ 871,640
Total, unrealized losses	(31,483)	(32,948)
Amortized Cost
Amortized Cost - Total available-for-sale debt securities	907,602	929,588
Fair Value
Fair Value, Total available-for-sale debt securities	876,119	896,640
Debt Securities, Available-for-Sale, Unrealized Loss Position [Line Items]
Less than 12 months, fair value	48,536	273,150
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	1,439	8,982
12 months or more, fair value	827,583	598,490
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ 30,044	$ 23,966
Total, number of holdings | holding	51	52
Total, fair value	$ 876,119	$ 871,640
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	31,483	32,948
CLO
Debt Securities, Available-for-sale [Abstract]
Amortized Cost - Total available-for-sale debt securities		2,108
Unrealized Gains		0
Unrealized Losses		(1)
Investment securities available-for-sale, at fair value		2,107
12 months or more, fair value		2,107
12 months or more, unrealized losses		$ (1)
Total, number of holdings | holding		1
Total, fair value		$ 2,107
Total, unrealized losses		(1)
Amortized Cost
Amortized Cost - Total available-for-sale debt securities		2,108
Fair Value
Fair Value, Total available-for-sale debt securities		2,107
Debt Securities, Available-for-Sale, Unrealized Loss Position [Line Items]
12 months or more, fair value		2,107
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss		$ 1
Total, number of holdings | holding		1
Total, fair value		$ 2,107
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss		1
Corporate debt
Debt Securities, Available-for-sale [Abstract]
Amortized Cost - Total available-for-sale debt securities	712,726	795,999
Unrealized Gains	0	0
Unrealized Losses	(103,967)	(91,587)
Investment securities available-for-sale, at fair value	608,759	704,412
Less than 12 months, fair value	8,805	692,990
Less than 12 months, unrealized losses	(1,297)	(89,692)
12 months or more, fair value	599,954	8,421
12 months or more, unrealized losses	$ (102,670)	$ (1,895)
Total, number of holdings | holding	92	105
Total, fair value	$ 608,759	$ 701,411
Total, unrealized losses	(103,967)	(91,587)
Amortized Cost
Amortized Cost - Total available-for-sale debt securities	712,726	795,999
Fair Value
Fair Value, Total available-for-sale debt securities	608,759	704,412
Debt Securities, Available-for-Sale, Unrealized Loss Position [Line Items]
Less than 12 months, fair value	8,805	692,990
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	1,297	89,692
12 months or more, fair value	599,954	8,421
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ 102,670	$ 1,895
Total, number of holdings | holding	92	105
Total, fair value	$ 608,759	$ 701,411
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	103,967	91,587
Private label MBS
Debt Securities, Available-for-sale [Abstract]
Amortized Cost - Total available-for-sale debt securities	47,485	48,895
Unrealized Gains	0	0
Unrealized Losses	(4,435)	(4,646)
Investment securities available-for-sale, at fair value	43,050	44,249
Less than 12 months, fair value	11,880	44,249
Less than 12 months, unrealized losses	(1,153)	$ (4,646)
12 months or more, fair value	31,170
12 months or more, unrealized losses	$ (3,282)
Total, number of holdings | holding	3	3
Total, fair value	$ 43,050	$ 44,249
Total, unrealized losses	(4,435)	(4,646)
Amortized Cost
Amortized Cost - Total available-for-sale debt securities	47,485	48,895
Fair Value
Fair Value, Total available-for-sale debt securities	43,050	44,249
Debt Securities, Available-for-Sale, Unrealized Loss Position [Line Items]
Less than 12 months, fair value	11,880	44,249
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	1,153	$ 4,646
12 months or more, fair value	31,170
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ 3,282
Total, number of holdings | holding	3	3
Total, fair value	$ 43,050	$ 44,249
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	4,435	4,646
Other
Debt Securities, Available-for-sale [Abstract]
Amortized Cost - Total available-for-sale debt securities	9,817	12,548
Unrealized Gains	0	0
Unrealized Losses	(911)	(350)
Investment securities available-for-sale, at fair value	8,906	12,198
Less than 12 months, fair value	4,789	12,198
Less than 12 months, unrealized losses	(211)	$ (350)
12 months or more, fair value	4,117
12 months or more, unrealized losses	$ (700)
Total, number of holdings | holding	2	4
Total, fair value	$ 8,906	$ 12,198
Total, unrealized losses	(911)	(350)
Amortized Cost
Amortized Cost - Total available-for-sale debt securities	9,817	12,548
Fair Value
Fair Value, Total available-for-sale debt securities	8,906	12,198
Debt Securities, Available-for-Sale, Unrealized Loss Position [Line Items]
Less than 12 months, fair value	4,789	12,198
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	211	$ 350
12 months or more, fair value	4,117
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ 700
Total, number of holdings | holding	2	4
Total, fair value	$ 8,906	$ 12,198
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	911	350
Pledged For Borrowings
Fair Value
Available-for-sale securities pledged	4,211,733	1,195,101
Pledged For Municipal Deposits
Fair Value
Available-for-sale securities pledged	$ 2,251,240	$ 2,573,072