Investment Securities (Summary Of Debt Securities Available-for-Sale) (Detail) $ in Thousands	Sep. 30, 2022 USD ($) holding	Dec. 31, 2021 USD ($) holding
Debt Securities, Available-for-sale [Abstract]
Amortized Cost - Total available-for-sale debt securities	$ 9,026,804	$ 4,227,697
Unrealized Gains	21	41,499
Unrealized Losses	(941,781)	(34,342)
Investment securities available-for-sale, at fair value	8,085,044	4,234,854
Less than 12 months, fair value	6,811,526	2,272,641
Less than 12 months, unrealized losses	(757,586)	(17,086)
12 months or more, fair value	1,271,502	558,515
12 months or more, unrealized losses	$ (184,195)	$ (17,256)
Total, number of holdings | holding	1,340	162
Total, fair value	$ 8,083,028	$ 2,831,156
Total, unrealized losses	(941,781)	(34,342)
Amortized Cost
Due in one year or less	59,790
Due after one year through five years	1,452,511
Due after five through ten years	1,437,643
Due after ten years	6,076,860
Amortized Cost - Total available-for-sale debt securities	9,026,804	4,227,697
Fair Value
Due in one year or less	58,824
Due after one year through five years	1,361,398
Due after five through ten years	1,306,402
Due after ten years	5,358,420
Fair Value, Total available-for-sale debt securities	8,085,044	4,234,854
Available-for-sale securities pledged	4,960,865	1,780,164
U.S. Treasury notes
Debt Securities, Available-for-sale [Abstract]
Amortized Cost - Total available-for-sale debt securities	755,414	398,664
Unrealized Gains	0	0
Unrealized Losses	(42,151)	(1,698)
Investment securities available-for-sale, at fair value	713,263	396,966
Less than 12 months, fair value	713,263	396,966
Less than 12 months, unrealized losses	$ (42,151)	$ (1,698)
Total, number of holdings | holding	23	8
Total, fair value	$ 713,263	$ 396,966
Total, unrealized losses	(42,151)	(1,698)
Amortized Cost
Amortized Cost - Total available-for-sale debt securities	755,414	398,664
Fair Value
Fair Value, Total available-for-sale debt securities	713,263	396,966
Government agency debentures
Debt Securities, Available-for-sale [Abstract]
Amortized Cost - Total available-for-sale debt securities	311,982
Unrealized Gains	0
Unrealized Losses	(42,954)
Investment securities available-for-sale, at fair value	269,028
Less than 12 months, fair value	269,028
Less than 12 months, unrealized losses	$ (42,954)
Total, number of holdings | holding	20
Total, fair value	$ 269,028
Total, unrealized losses	(42,954)
Amortized Cost
Amortized Cost - Total available-for-sale debt securities	311,982
Fair Value
Fair Value, Total available-for-sale debt securities	269,028
Municipal bonds and notes
Debt Securities, Available-for-sale [Abstract]
Amortized Cost - Total available-for-sale debt securities	1,842,985
Unrealized Gains	0
Unrealized Losses	(145,840)
Investment securities available-for-sale, at fair value	1,697,145
Less than 12 months, fair value	1,696,419
Less than 12 months, unrealized losses	$ (145,840)
Total, number of holdings | holding	499
Total, fair value	$ 1,696,419
Total, unrealized losses	(145,840)
Amortized Cost
Amortized Cost - Total available-for-sale debt securities	1,842,985
Fair Value
Fair Value, Total available-for-sale debt securities	1,697,145
Agency CMO
Debt Securities, Available-for-sale [Abstract]
Amortized Cost - Total available-for-sale debt securities	68,886	88,109
Unrealized Gains	0	2,326
Unrealized Losses	(5,025)	(51)
Investment securities available-for-sale, at fair value	63,861	90,384
Less than 12 months, fair value	62,951	7,895
Less than 12 months, unrealized losses	(5,013)	$ (51)
12 months or more, fair value	910
12 months or more, unrealized losses	$ (12)
Total, number of holdings | holding	39	2
Total, fair value	$ 63,861	$ 7,895
Total, unrealized losses	(5,025)	(51)
Amortized Cost
Amortized Cost - Total available-for-sale debt securities	68,886	88,109
Fair Value
Fair Value, Total available-for-sale debt securities	63,861	90,384
Agency MBS
Debt Securities, Available-for-sale [Abstract]
Amortized Cost - Total available-for-sale debt securities	2,533,669	1,568,293
Unrealized Gains	21	36,130
Unrealized Losses	(336,341)	(11,020)
Investment securities available-for-sale, at fair value	2,197,349	1,593,403
Less than 12 months, fair value	1,794,195	506,602
Less than 12 months, unrealized losses	(252,060)	(7,354)
12 months or more, fair value	401,864	110,687
12 months or more, unrealized losses	$ (84,281)	$ (3,666)
Total, number of holdings | holding	460	70
Total, fair value	$ 2,196,059	$ 617,289
Total, unrealized losses	(336,341)	(11,020)
Amortized Cost
Amortized Cost - Total available-for-sale debt securities	2,533,669	1,568,293
Fair Value
Fair Value, Total available-for-sale debt securities	2,197,349	1,593,403
Agency CMBS
Debt Securities, Available-for-sale [Abstract]
Amortized Cost - Total available-for-sale debt securities	1,697,243	1,248,548
Unrealized Gains	0	2,537
Unrealized Losses	(241,324)	(18,544)
Investment securities available-for-sale, at fair value	1,455,919	1,232,541
Less than 12 months, fair value	991,740	632,213
Less than 12 months, unrealized losses	(154,725)	(6,163)
12 months or more, fair value	464,179	335,480
12 months or more, unrealized losses	$ (86,599)	$ (12,381)
Total, number of holdings | holding	132	28
Total, fair value	$ 1,455,919	$ 967,693
Total, unrealized losses	(241,324)	(18,544)
Amortized Cost
Amortized Cost - Total available-for-sale debt securities	1,697,243	1,248,548
Fair Value
Fair Value, Total available-for-sale debt securities	1,455,919	1,232,541
CMBS
Debt Securities, Available-for-sale [Abstract]
Amortized Cost - Total available-for-sale debt securities	949,535	887,640
Unrealized Gains	0	506
Unrealized Losses	(26,607)	(1,883)
Investment securities available-for-sale, at fair value	922,928	886,263
Less than 12 months, fair value	534,261	724,762
Less than 12 months, unrealized losses	(14,954)	(1,744)
12 months or more, fair value	388,667	81,253
12 months or more, unrealized losses	$ (11,653)	$ (139)
Total, number of holdings | holding	53	50
Total, fair value	$ 922,928	$ 806,015
Total, unrealized losses	(26,607)	(1,883)
Amortized Cost
Amortized Cost - Total available-for-sale debt securities	949,535	887,640
Fair Value
Fair Value, Total available-for-sale debt securities	922,928	886,263
CLO
Debt Securities, Available-for-sale [Abstract]
Amortized Cost - Total available-for-sale debt securities	7,219	21,860
Unrealized Gains	0	0
Unrealized Losses	(16)	(13)
Investment securities available-for-sale, at fair value	7,203	21,847
12 months or more, fair value	7,203	21,848
12 months or more, unrealized losses	$ (16)	$ (13)
Total, number of holdings | holding	1	1
Total, fair value	$ 7,203	$ 21,848
Total, unrealized losses	(16)	(13)
Amortized Cost
Amortized Cost - Total available-for-sale debt securities	7,219	21,860
Fair Value
Fair Value, Total available-for-sale debt securities	7,203	21,847
Corporate debt
Debt Securities, Available-for-sale [Abstract]
Amortized Cost - Total available-for-sale debt securities	797,931	14,583
Unrealized Gains	0	0
Unrealized Losses	(95,759)	(1,133)
Investment securities available-for-sale, at fair value	702,172	13,450
Less than 12 months, fair value	693,493	4,203
Less than 12 months, unrealized losses	(94,125)	(76)
12 months or more, fair value	8,679	9,247
12 months or more, unrealized losses	$ (1,634)	$ (1,057)
Total, number of holdings | holding	106	3
Total, fair value	$ 702,172	$ 13,450
Total, unrealized losses	(95,759)	(1,133)
Amortized Cost
Amortized Cost - Total available-for-sale debt securities	797,931	14,583
Fair Value
Fair Value, Total available-for-sale debt securities	702,172	13,450
Private label MBS
Debt Securities, Available-for-sale [Abstract]
Amortized Cost - Total available-for-sale debt securities	49,408
Unrealized Gains	0
Unrealized Losses	(5,098)
Investment securities available-for-sale, at fair value	44,310
Less than 12 months, fair value	44,310
Less than 12 months, unrealized losses	$ (5,098)
Total, number of holdings | holding	3
Total, fair value	$ 44,310
Total, unrealized losses	(5,098)
Amortized Cost
Amortized Cost - Total available-for-sale debt securities	49,408
Fair Value
Fair Value, Total available-for-sale debt securities	44,310
Other
Debt Securities, Available-for-sale [Abstract]
Amortized Cost - Total available-for-sale debt securities	12,532
Unrealized Gains	0
Unrealized Losses	(666)
Investment securities available-for-sale, at fair value	11,866
Less than 12 months, fair value	11,866
Less than 12 months, unrealized losses	$ (666)
Total, number of holdings | holding	4
Total, fair value	$ 11,866
Total, unrealized losses	(666)
Amortized Cost
Amortized Cost - Total available-for-sale debt securities	12,532
Fair Value
Fair Value, Total available-for-sale debt securities	11,866
Pledged For Borrowings
Fair Value
Available-for-sale securities pledged	1,282,501	924,841
Pledged For Municipal Deposits
Fair Value
Available-for-sale securities pledged	$ 3,678,364	$ 855,323