Investment Securities - Summary of Investment Securities (Detail) - USD ($) $ in Thousands		Jun. 30, 2025	Dec. 31, 2024
Schedule of Investments [Line Items]
Amortized cost		$ 10,189,481	$ 9,720,415
Unrealized Gains		42,579	12,952
Unrealized Losses		(610,839)	(725,900)
Allowance for Credit Losses		(867)	(867)
Fair Value	[1]	9,620,354	9,006,600
Debt Securities, Available-For-Sale
Schedule of Investments [Line Items]
Interest receivable		36,800	35,200
Government agency debentures
Schedule of Investments [Line Items]
Amortized cost		222,808	222,767
Unrealized Gains		0	0
Unrealized Losses		(30,372)	(36,341)
Allowance for Credit Losses		0	0
Fair Value		192,436	186,426
Municipal bonds and notes
Schedule of Investments [Line Items]
Amortized cost		117,562	123,885
Unrealized Gains		0	2
Unrealized Losses		(13,754)	(13,011)
Allowance for Credit Losses		0	0
Fair Value		103,808	110,876
Agency CMO
Schedule of Investments [Line Items]
Amortized cost		29,439	32,193
Unrealized Gains		0	0
Unrealized Losses		(2,326)	(3,150)
Allowance for Credit Losses		0	0
Fair Value		27,113	29,043
Agency MBS
Schedule of Investments [Line Items]
Amortized cost		4,980,846	4,760,541
Unrealized Gains		36,060	11,654
Unrealized Losses		(185,301)	(252,410)
Allowance for Credit Losses		0	0
Fair Value		4,831,605	4,519,785
Agency CMBS
Schedule of Investments [Line Items]
Amortized cost		3,558,974	3,400,021
Unrealized Gains		5,201	84
Unrealized Losses		(339,977)	(365,713)
Allowance for Credit Losses		0	0
Fair Value		3,224,198	3,034,392
CMBS
Schedule of Investments [Line Items]
Amortized cost		791,930	630,985
Unrealized Gains		1,054	411
Unrealized Losses		(2,852)	(6,008)
Allowance for Credit Losses		0	0
Fair Value		790,132	625,388
Corporate debt
Schedule of Investments [Line Items]
Amortized cost		435,483	496,087
Unrealized Gains		264	801
Unrealized Losses		(31,507)	(43,755)
Allowance for Credit Losses		(867)	(867)
Fair Value		403,373	452,266
Private label MBS
Schedule of Investments [Line Items]
Amortized cost		42,571	44,081
Unrealized Gains		0	0
Unrealized Losses		(4,207)	(4,862)
Allowance for Credit Losses		0	0
Fair Value		38,364	39,219
Other
Schedule of Investments [Line Items]
Amortized cost		9,868	9,855
Unrealized Gains		0	0
Unrealized Losses		(543)	(650)
Allowance for Credit Losses		0	0
Fair Value		$ 9,325	$ 9,205

[1] Investment securities available-for-sale had an amortized cost basis of $10,189,481 at June 30, 2025, and $9,720,415 at December 31, 2024.