Balance Sheet Offsetting - Financial Instruments Derivative Assets Liabilities and Resell Agreements Net of Amount Not Offset (Detail) - USD ($) $ in Thousands	Mar. 31, 2026	Dec. 31, 2025
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Net Amount Recognized, Derivatives, Financial Assets	$ 52,094	$ 88,337
Gross Amounts Not Offset, Financial Instruments, Total Derivatives, Financial Assets	(46,051)	(12,302)
Gross Amount Not Offset Collateral, Derivatives, Financial Assets	(5,796)	(69,691)
Net Amount, Derivatives, Financial Assets	247	6,344
Net Amount Recognized, Resell agreements, Financial Assets	0	9,650
Gross Amounts Not Offset Financial Instruments, Resell Agreements	0	0
Gross Amounts Not Offset Collateral, Resell Agreements, Financial Assets	0	(9,650)
Net Amount, Financial Assets, Resell Agreements	0	0
Net Amount Recognized, Total Financial Assets	52,094	97,987
Gross Amounts Not Offset Collateral, Financial Assets	(5,796)	(79,341)
Net Amount, Financial Assets	247	6,344
Net Amount Recognized, Derivatives, Financial Liabilities	146,428	22,504
Gross Amounts Not Offset Financial Instruments, Total Derivatives, Financial Liabilities	(46,051)	(12,302)
Gross Amounts Not Offset Collateral, Derivatives, Financial Liabilities	(99,785)	(10,181)
Net Amount, Derivatives, Financial Liabilities	592	21
Net Amount Recognized, Repurchase Agreements, Financial Liabilities	4,101,707	4,525,855
Gross Amounts Not Offset Financial Instruments, Repurchase Agreements, Financial Liabilities	0	0
Gross Amounts Not Offset Collateral, Repurchase Agreements, Financial Liabilities	(4,101,707)	(4,525,855)
Net Amount, Repurchase Agreements, Financial Liabilities	0	0
Net Amount Recognized, Total Financial Liabilities	4,248,135	4,548,359
Gross Amounts Not Offset Collateral, Financial Liabilities	(4,201,492)	(4,536,036)
Net Amount, Financial Liabilities	592	21
Counterparty H
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Net Amount Recognized, Derivatives, Financial Assets	14,876	35,230
Gross Amounts Not Offset, Financial Instruments, Total Derivatives, Financial Assets	(14,876)	(907)
Gross Amount Not Offset Collateral, Derivatives, Financial Assets	0	(31,270)
Net Amount, Derivatives, Financial Assets	0	3,053
Net Amount Recognized, Derivatives, Financial Liabilities	61,781	907
Gross Amounts Not Offset Financial Instruments, Total Derivatives, Financial Liabilities	(14,876)	(907)
Gross Amounts Not Offset Collateral, Derivatives, Financial Liabilities	(46,905)	0
Net Amount, Derivatives, Financial Liabilities	0	0
Counterparty F
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Net Amount Recognized, Derivatives, Financial Assets	15,293	20,242
Gross Amounts Not Offset, Financial Instruments, Total Derivatives, Financial Assets	(15,293)	(290)
Gross Amount Not Offset Collateral, Derivatives, Financial Assets	0	(19,495)
Net Amount, Derivatives, Financial Assets	0	457
Net Amount Recognized, Derivatives, Financial Liabilities	26,915	290
Gross Amounts Not Offset Financial Instruments, Total Derivatives, Financial Liabilities	(15,293)	(290)
Gross Amounts Not Offset Collateral, Derivatives, Financial Liabilities	(11,622)	0
Net Amount, Derivatives, Financial Liabilities	0	0
Counterparty B
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Net Amount Recognized, Derivatives, Financial Assets	7,455	13,619
Gross Amounts Not Offset, Financial Instruments, Total Derivatives, Financial Assets	(7,455)	(1,184)
Gross Amount Not Offset Collateral, Derivatives, Financial Assets	0	(10,789)
Net Amount, Derivatives, Financial Assets	0	1,646
Net Amount Recognized, Derivatives, Financial Liabilities	20,147	1,184
Gross Amounts Not Offset Financial Instruments, Total Derivatives, Financial Liabilities	(7,455)	(1,184)
Gross Amounts Not Offset Collateral, Derivatives, Financial Liabilities	(12,692)	0
Net Amount, Derivatives, Financial Liabilities	0	0
Counterparty E
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Net Amount Recognized, Derivatives, Financial Assets	7,876	7,298
Gross Amounts Not Offset, Financial Instruments, Total Derivatives, Financial Assets	(4,377)	(6,418)
Gross Amount Not Offset Collateral, Derivatives, Financial Assets	(3,450)	(220)
Net Amount, Derivatives, Financial Assets	49	660
Net Amount Recognized, Derivatives, Financial Liabilities	4,377	6,418
Gross Amounts Not Offset Financial Instruments, Total Derivatives, Financial Liabilities	(4,377)	(6,418)
Gross Amounts Not Offset Collateral, Derivatives, Financial Liabilities	0	0
Net Amount, Derivatives, Financial Liabilities	0	0
Other counterparties
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Net Amount Recognized, Derivatives, Financial Assets	6,594	11,948
Gross Amounts Not Offset, Financial Instruments, Total Derivatives, Financial Assets	(4,050)	(3,503)
Gross Amount Not Offset Collateral, Derivatives, Financial Assets	(2,346)	(7,917)
Net Amount, Derivatives, Financial Assets	198	528
Net Amount Recognized, Derivatives, Financial Liabilities	33,208	13,705
Gross Amounts Not Offset Financial Instruments, Total Derivatives, Financial Liabilities	(4,050)	(3,503)
Gross Amounts Not Offset Collateral, Derivatives, Financial Liabilities	(28,566)	(10,181)
Net Amount, Derivatives, Financial Liabilities	$ 592	$ 21