Investment Securities - Summary of Gross Unrealized Losses and Fair Value of Available-for-Sale Securities (Detail) $ in Thousands	Mar. 31, 2025 USD ($) holding	Dec. 31, 2024 USD ($) holding
Schedule of Investments [Line Items]
Less than 12 months, fair value	$ 2,476,808	$ 4,094,196
Less Than 12 Months, Unrealized Losses	(25,459)	(64,068)
12 months or more, fair value	3,902,600	4,043,216
12 Months or More, Unrealized Losses	$ (588,049)	$ (661,832)
Total, number of holdings | holding	699	751
Total, fair value	$ 6,379,408	$ 8,137,412
Total, unrealized losses	(613,508)	(725,900)
Government agency debentures
Schedule of Investments [Line Items]
12 months or more, fair value	192,341	186,427
12 Months or More, Unrealized Losses	$ (30,448)	$ (36,341)
Total, number of holdings | holding	15	15
Total, fair value	$ 192,341	$ 186,427
Total, unrealized losses	(30,448)	(36,341)
Municipal bonds and notes
Schedule of Investments [Line Items]
Less than 12 months, fair value	415	859
Less Than 12 Months, Unrealized Losses	(1)	(1)
12 months or more, fair value	106,816	108,013
12 Months or More, Unrealized Losses	$ (13,706)	$ (13,010)
Total, number of holdings | holding	53	57
Total, fair value	$ 107,231	$ 108,872
Total, unrealized losses	(13,707)	(13,011)
Agency CMO
Schedule of Investments [Line Items]
12 months or more, fair value	28,285	29,043
12 Months or More, Unrealized Losses	$ (2,570)	$ (3,150)
Total, number of holdings | holding	28	28
Total, fair value	$ 28,285	$ 29,043
Total, unrealized losses	(2,570)	(3,150)
Agency MBS
Schedule of Investments [Line Items]
Less than 12 months, fair value	1,296,745	2,624,722
Less Than 12 Months, Unrealized Losses	(8,846)	(31,539)
12 months or more, fair value	1,244,453	1,246,818
12 Months or More, Unrealized Losses	$ (189,187)	$ (220,871)
Total, number of holdings | holding	337	370
Total, fair value	$ 2,541,198	$ 3,871,540
Total, unrealized losses	(198,033)	(252,410)
Agency CMBS
Schedule of Investments [Line Items]
Less than 12 months, fair value	1,071,143	1,468,615
Less Than 12 Months, Unrealized Losses	(16,294)	(32,528)
12 months or more, fair value	1,572,848	1,540,263
12 Months or More, Unrealized Losses	$ (308,539)	$ (333,185)
Total, number of holdings | holding	172	185
Total, fair value	$ 2,643,991	$ 3,008,878
Total, unrealized losses	(324,833)	(365,713)
CMBS
Schedule of Investments [Line Items]
Less than 12 months, fair value	98,625
Less Than 12 Months, Unrealized Losses	(180)
12 months or more, fair value	291,626	457,423
12 Months or More, Unrealized Losses	$ (2,899)	$ (6,008)
Total, number of holdings | holding	32	32
Total, fair value	$ 390,251	$ 457,423
Total, unrealized losses	(3,079)	(6,008)
Corporate debt
Schedule of Investments [Line Items]
Less than 12 months, fair value	9,880
Less Than 12 Months, Unrealized Losses	(138)
12 months or more, fair value	417,790	426,805
12 Months or More, Unrealized Losses	$ (35,925)	$ (43,755)
Total, number of holdings | holding	57	59
Total, fair value	$ 427,670	$ 426,805
Total, unrealized losses	(36,063)	(43,755)
Private label MBS
Schedule of Investments [Line Items]
Less than 12 months, fair value	0	0
Less Than 12 Months, Unrealized Losses	0	0
12 months or more, fair value	39,158	39,219
12 Months or More, Unrealized Losses	$ (4,197)	$ (4,862)
Total, number of holdings | holding	3	3
Total, fair value	$ 39,158	$ 39,219
Total, unrealized losses	(4,197)	(4,862)
Other
Schedule of Investments [Line Items]
12 months or more, fair value	9,283	9,205
12 Months or More, Unrealized Losses	$ (578)	$ (650)
Total, number of holdings | holding	2	2
Total, fair value	$ 9,283	$ 9,205
Total, unrealized losses	$ (578)	$ (650)