Investment Securities - Summary of Gross Unrealized Losses and Fair Value of Available-for-Sale Securities (Detail) $ in Thousands	Jun. 30, 2025 USD ($) holding	Dec. 31, 2024 USD ($) holding
Schedule of Investments [Line Items]
Less than 12 months, fair value	$ 2,325,248	$ 4,094,196
Less Than 12 Months, Unrealized Losses	(34,392)	(64,068)
12 months or more, fair value	3,774,523	4,043,216
12 Months or More, Unrealized Losses	$ (576,447)	$ (661,832)
Total, number of holdings | holding	673	751
Total, fair value	$ 6,099,771	$ 8,137,412
Total, unrealized losses	(610,839)	(725,900)
Government agency debentures
Schedule of Investments [Line Items]
12 months or more, fair value	192,436	186,427
12 Months or More, Unrealized Losses	$ (30,372)	$ (36,341)
Total, number of holdings | holding	15	15
Total, fair value	$ 192,436	$ 186,427
Total, unrealized losses	(30,372)	(36,341)
Municipal bonds and notes
Schedule of Investments [Line Items]
Less than 12 months, fair value		859
Less Than 12 Months, Unrealized Losses		(1)
12 months or more, fair value	103,032	108,013
12 Months or More, Unrealized Losses	$ (13,754)	$ (13,010)
Total, number of holdings | holding	38	57
Total, fair value	$ 103,032	$ 108,872
Total, unrealized losses	(13,754)	(13,011)
Agency CMO
Schedule of Investments [Line Items]
12 months or more, fair value	27,113	29,043
12 Months or More, Unrealized Losses	$ (2,326)	$ (3,150)
Total, number of holdings | holding	28	28
Total, fair value	$ 27,113	$ 29,043
Total, unrealized losses	(2,326)	(3,150)
Agency MBS
Schedule of Investments [Line Items]
Less than 12 months, fair value	822,663	2,624,722
Less Than 12 Months, Unrealized Losses	(5,939)	(31,539)
12 months or more, fair value	1,218,266	1,246,818
12 Months or More, Unrealized Losses	$ (179,362)	$ (220,871)
Total, number of holdings | holding	326	370
Total, fair value	$ 2,040,929	$ 3,871,540
Total, unrealized losses	(185,301)	(252,410)
Agency CMBS
Schedule of Investments [Line Items]
Less than 12 months, fair value	1,280,991	1,468,615
Less Than 12 Months, Unrealized Losses	(27,776)	(32,528)
12 months or more, fair value	1,558,697	1,540,263
12 Months or More, Unrealized Losses	$ (312,201)	$ (333,185)
Total, number of holdings | holding	178	185
Total, fair value	$ 2,839,688	$ 3,008,878
Total, unrealized losses	(339,977)	(365,713)
CMBS
Schedule of Investments [Line Items]
Less than 12 months, fair value	213,594
Less Than 12 Months, Unrealized Losses	(676)
12 months or more, fair value	252,181	457,423
12 Months or More, Unrealized Losses	$ (2,176)	$ (6,008)
Total, number of holdings | holding	32	32
Total, fair value	$ 465,775	$ 457,423
Total, unrealized losses	(2,852)	(6,008)
Corporate debt
Schedule of Investments [Line Items]
Less than 12 months, fair value	8,000
Less Than 12 Months, Unrealized Losses	(1)
12 months or more, fair value	375,109	426,805
12 Months or More, Unrealized Losses	$ (31,506)	$ (43,755)
Total, number of holdings | holding	51	59
Total, fair value	$ 383,109	$ 426,805
Total, unrealized losses	(31,507)	(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	38,364	39,219
12 Months or More, Unrealized Losses	$ (4,207)	$ (4,862)
Total, number of holdings | holding	3	3
Total, fair value	$ 38,364	$ 39,219
Total, unrealized losses	(4,207)	(4,862)
Other
Schedule of Investments [Line Items]
12 months or more, fair value	9,325	9,205
12 Months or More, Unrealized Losses	$ (543)	$ (650)
Total, number of holdings | holding	2	2
Total, fair value	$ 9,325	$ 9,205
Total, unrealized losses	$ (543)	$ (650)