Balance Sheet Offsetting - Financial Instruments Derivative Assets Liabilities and Resell Agreements Net of Amount Not Offset (Detail) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Net Amount Recognized, Derivatives, Financial Assets	$ 130,330	$ 118,994
Gross Amounts Not Offset, Financial Instruments, Total Derivatives, Financial Assets	(29,402)	(62,528)
Gross Amount Not Offset Collateral, Derivatives, Financial Assets	(100,589)	(55,968)
Net Amount, Derivatives, Financial Assets	339	498
Net Amount Recognized, Resell agreements, Financial Assets	84,650	87,150
Gross Amounts Not Offset Financial Instruments, Resell Agreements	0	0
Gross Amounts Not Offset Collateral, Resell Agreements, Financial Assets	(84,650)	(87,150)
Net Amount, Financial Assets, Resell Agreements	0	0
Net Amount Recognized, Total Financial Assets	214,980	206,144
Gross Amounts Not Offset Collateral, Financial Assets	(185,239)	(143,118)
Net Amount, Financial Assets	339	498
Net Amount Recognized, Derivatives, Financial Liabilities	29,402	73,829
Gross Amounts Not Offset Financial Instruments, Total Derivatives, Financial Liabilities	(29,402)	(62,528)
Gross Amounts Not Offset Collateral, Derivatives, Financial Liabilities	0	(9,330)
Net Amount, Derivatives, Financial Liabilities	0	1,971
Net Amount Recognized, Repurchase Agreements, Financial Liabilities	3,569,870	4,660,641
Gross Amounts Not Offset Financial Instruments, Repurchase Agreements, Financial Liabilities	0	0
Gross Amounts Not Offset Collateral, Repurchase Agreements, Financial Liabilities	(3,569,870)	(4,660,641)
Net Amount, Repurchase Agreements, Financial Liabilities	0	0
Net Amount Recognized, Total Financial Liabilities	3,599,272	4,734,470
Gross Amounts Not Offset Collateral, Financial Liabilities	(3,569,870)	(4,669,971)
Net Amount, Financial Liabilities	0	1,971
Counterparty B
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Net Amount Recognized, Derivatives, Financial Assets	32,143	39,370
Gross Amounts Not Offset, Financial Instruments, Total Derivatives, Financial Assets	(9,548)	(24,500)
Gross Amount Not Offset Collateral, Derivatives, Financial Assets	(22,595)	(14,870)
Net Amount, Derivatives, Financial Assets	0	0
Net Amount Recognized, Derivatives, Financial Liabilities	9,548	24,500
Gross Amounts Not Offset Financial Instruments, Total Derivatives, Financial Liabilities	(9,548)	(24,500)
Gross Amounts Not Offset Collateral, Derivatives, Financial Liabilities	0	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	16,312	14,430
Gross Amounts Not Offset, Financial Instruments, Total Derivatives, Financial Assets	(896)	(47)
Gross Amount Not Offset Collateral, Derivatives, Financial Assets	(15,240)	(14,131)
Net Amount, Derivatives, Financial Assets	176	252
Net Amount Recognized, Derivatives, Financial Liabilities	896	47
Gross Amounts Not Offset Financial Instruments, Total Derivatives, Financial Liabilities	(896)	(47)
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	18,387	17,297
Gross Amounts Not Offset, Financial Instruments, Total Derivatives, Financial Assets	(8,839)	(17,297)
Gross Amount Not Offset Collateral, Derivatives, Financial Assets	(9,463)	0
Net Amount, Derivatives, Financial Assets	85	0
Net Amount Recognized, Derivatives, Financial Liabilities	8,839	27,747
Gross Amounts Not Offset Financial Instruments, Total Derivatives, Financial Liabilities	(8,839)	(17,297)
Gross Amounts Not Offset Collateral, Derivatives, Financial Liabilities	0	(8,479)
Net Amount, Derivatives, Financial Liabilities	0	1,971
Counterparty G
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Net Amount Recognized, Derivatives, Financial Assets	10,484	10,660
Gross Amounts Not Offset, Financial Instruments, Total Derivatives, Financial Assets	0	0
Gross Amount Not Offset Collateral, Derivatives, Financial Assets	(10,430)	(10,660)
Net Amount, Derivatives, Financial Assets	54	0
Net Amount Recognized, Derivatives, Financial Liabilities		0
Gross Amounts Not Offset Financial Instruments, Total Derivatives, Financial Liabilities		0
Gross Amounts Not Offset Collateral, Derivatives, Financial Liabilities		0
Net Amount, Derivatives, Financial Liabilities		0
Other counterparties
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Net Amount Recognized, Derivatives, Financial Assets	53,004	37,237
Gross Amounts Not Offset, Financial Instruments, Total Derivatives, Financial Assets	(10,119)	(20,684)
Gross Amount Not Offset Collateral, Derivatives, Financial Assets	(42,861)	(16,307)
Net Amount, Derivatives, Financial Assets	24	246
Net Amount Recognized, Derivatives, Financial Liabilities	10,119	21,535
Gross Amounts Not Offset Financial Instruments, Total Derivatives, Financial Liabilities	(10,119)	(20,684)
Gross Amounts Not Offset Collateral, Derivatives, Financial Liabilities	0	(851)
Net Amount, Derivatives, Financial Liabilities	$ 0	$ 0