Balance Sheet Offsetting - Financial Instruments Derivative Assets Liabilities and Resell Agreements Net of Amount Not Offset (Detail) - USD ($) $ in Thousands	Jun. 30, 2026	Dec. 31, 2025
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Net Amount Recognized, Derivatives, Financial Assets	$ 65,595	$ 88,337
Gross Amounts Not Offset, Financial Instruments, Total Derivatives, Financial Assets	(38,202)	(12,302)
Gross Amount Not Offset Collateral, Derivatives, Financial Assets	(23,024)	(69,691)
Net Amount, Derivatives, Financial Assets	4,369	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	65,595	97,987
Gross Amounts Not Offset Collateral, Financial Assets	(23,024)	(79,341)
Net Amount, Financial Assets	4,369	6,344
Net Amount Recognized, Derivatives, Financial Liabilities	50,498	22,504
Gross Amounts Not Offset Financial Instruments, Total Derivatives, Financial Liabilities	(38,202)	(12,302)
Gross Amounts Not Offset Collateral, Derivatives, Financial Liabilities	(12,203)	(10,181)
Net Amount, Derivatives, Financial Liabilities	93	21
Net Amount Recognized, Repurchase Agreements, Financial Liabilities	4,886,598	4,525,855
Gross Amounts Not Offset Financial Instruments, Repurchase Agreements, Financial Liabilities	0	0
Gross Amounts Not Offset Collateral, Repurchase Agreements, Financial Liabilities	(4,886,598)	(4,525,855)
Net Amount, Repurchase Agreements, Financial Liabilities	0	0
Net Amount Recognized, Total Financial Liabilities	4,937,096	4,548,359
Gross Amounts Not Offset Collateral, Financial Liabilities	(4,898,801)	(4,536,036)
Net Amount, Financial Liabilities	93	21
Counterparty H
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Net Amount Recognized, Derivatives, Financial Assets	21,057	35,230
Gross Amounts Not Offset, Financial Instruments, Total Derivatives, Financial Assets	(15,708)	(907)
Gross Amount Not Offset Collateral, Derivatives, Financial Assets	(2,660)	(31,270)
Net Amount, Derivatives, Financial Assets	2,689	3,053
Net Amount Recognized, Derivatives, Financial Liabilities	15,708	907
Gross Amounts Not Offset Financial Instruments, Total Derivatives, Financial Liabilities	(15,708)	(907)
Gross Amounts Not Offset Collateral, Derivatives, Financial Liabilities	0	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	14,833	20,242
Gross Amounts Not Offset, Financial Instruments, Total Derivatives, Financial Assets	(7,052)	(290)
Gross Amount Not Offset Collateral, Derivatives, Financial Assets	(7,781)	(19,495)
Net Amount, Derivatives, Financial Assets	0	457
Net Amount Recognized, Derivatives, Financial Liabilities	7,052	290
Gross Amounts Not Offset Financial Instruments, Total Derivatives, Financial Liabilities	(7,052)	(290)
Gross Amounts Not Offset Collateral, Derivatives, Financial Liabilities	0	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	8,137	13,619
Gross Amounts Not Offset, Financial Instruments, Total Derivatives, Financial Assets	(8,137)	(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	11,030	1,184
Gross Amounts Not Offset Financial Instruments, Total Derivatives, Financial Liabilities	(8,137)	(1,184)
Gross Amounts Not Offset Collateral, Derivatives, Financial Liabilities	(2,893)	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	10,999	7,298
Gross Amounts Not Offset, Financial Instruments, Total Derivatives, Financial Assets	(2,107)	(6,418)
Gross Amount Not Offset Collateral, Derivatives, Financial Assets	(8,260)	(220)
Net Amount, Derivatives, Financial Assets	632	660
Net Amount Recognized, Derivatives, Financial Liabilities	2,107	6,418
Gross Amounts Not Offset Financial Instruments, Total Derivatives, Financial Liabilities	(2,107)	(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	10,569	11,948
Gross Amounts Not Offset, Financial Instruments, Total Derivatives, Financial Assets	(5,198)	(3,503)
Gross Amount Not Offset Collateral, Derivatives, Financial Assets	(4,323)	(7,917)
Net Amount, Derivatives, Financial Assets	1,048	528
Net Amount Recognized, Derivatives, Financial Liabilities	14,601	13,705
Gross Amounts Not Offset Financial Instruments, Total Derivatives, Financial Liabilities	(5,198)	(3,503)
Gross Amounts Not Offset Collateral, Derivatives, Financial Liabilities	(9,310)	(10,181)
Net Amount, Derivatives, Financial Liabilities	$ 93	$ 21