Investment Securities - Summary of Debt Securities Held-to-Maturity (Detail) - USD ($) $ in Thousands	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Financing Receivable, Credit Quality Indicator [Line Items]
Amortized Cost	$ 8,444,362	$ 7,074,797
Unrealized Gains	1,502	22,167
Unrealized Losses	(992,741)	(832,341)
Fair Value	7,453,123	6,264,623
Allowance for Credit Losses	171	209	$ 182	$ 214
Net Carrying Value	8,444,191	7,074,588
Held-to-maturity Securities
Financing Receivable, Credit Quality Indicator [Line Items]
Interest receivable	30,500	24,900
Agency CMO
Financing Receivable, Credit Quality Indicator [Line Items]
Amortized Cost	19,847	23,470
Unrealized Gains	0	0
Unrealized Losses	(1,671)	(1,728)
Fair Value	18,176	21,742
Allowance for Credit Losses	0	0
Net Carrying Value	19,847	23,470
Agency MBS
Financing Receivable, Credit Quality Indicator [Line Items]
Amortized Cost	3,109,411	2,409,521
Unrealized Gains	771	1,141
Unrealized Losses	(333,039)	(284,776)
Fair Value	2,777,143	2,125,886
Allowance for Credit Losses	0	0
Net Carrying Value	3,109,411	2,409,521
Agency CMBS
Financing Receivable, Credit Quality Indicator [Line Items]
Amortized Cost	4,357,505	3,625,627
Unrealized Gains	414	18,586
Unrealized Losses	(613,914)	(514,534)
Fair Value	3,744,005	3,129,679
Allowance for Credit Losses	0	0
Net Carrying Value	4,357,505	3,625,627
Municipal bonds and notes
Financing Receivable, Credit Quality Indicator [Line Items]
Amortized Cost	891,909	916,104
Unrealized Gains	317	2,440
Unrealized Losses	(40,266)	(24,877)
Fair Value	851,960	893,667
Allowance for Credit Losses	171	209
Net Carrying Value	891,738	915,895
CMBS
Financing Receivable, Credit Quality Indicator [Line Items]
Amortized Cost	65,690	100,075
Unrealized Gains	0	0
Unrealized Losses	(3,851)	(6,426)
Fair Value	61,839	93,649
Allowance for Credit Losses	0	0
Net Carrying Value	$ 65,690	$ 100,075

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