Balance Sheet Offsetting - Financial Instruments Derivative Assets Liabilities and Resell Agreements Net of Amount Not Offset (Detail) - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Net Amount Recognized, Derivatives, Financial Assets	$ 61,994	$ 23,339
Gross Amounts Not Offset, Financial Instruments, Total Derivatives, Financial Assets	(51,552)	(23,339)
Gross Amount Not Offset Collateral, Derivatives, Financial Assets	(10,442)	0
Net Amount, Derivatives, Financial Assets	0	0
Net Amount Recognized, Resell agreements, Financial Assets	9,650	7,903
Gross Amounts Not Offset Financial Instruments, Resell Agreements	0	0
Gross Amounts Not Offset Collateral, Resell Agreements, Financial Assets	(9,650)	(7,903)
Net Amount, Financial Assets, Resell Agreements	0	0
Net Amount Recognized, Total Financial Assets	71,644	31,242
Gross Amounts Not Offset Collateral, Financial Assets	(20,092)	(7,903)
Net Amount, Financial Assets	0	0
Net Amount Recognized, Derivatives, Financial Liabilities	222,814	114,019
Gross Amounts Not Offset Financial Instruments, Total Derivatives, Financial Liabilities	(51,552)	(23,339)
Gross Amounts Not Offset Collateral, Derivatives, Financial Liabilities	(170,983)	(90,573)
Net Amount, Derivatives, Financial Liabilities	279	107
Net Amount Recognized, Repurchase Agreements, Financial Liabilities	1,664,685	2,740,799
Gross Amounts Not Offset Financial Instruments, Repurchase Agreements, Financial Liabilities	0	0
Gross Amounts Not Offset Collateral, Repurchase Agreements, Financial Liabilities	(1,664,685)	(2,740,799)
Net Amount, Repurchase Agreements, Financial Liabilities	0	0
Net Amount Recognized, Financial Liabilities	1,887,499	2,854,818
Gross Amounts Not Offset Collateral, Financial Liabilities	(1,835,668)	(2,831,372)
Net Amount, Financial Liabilities	279	107
Counterparty A [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Net Amount Recognized, Derivatives, Financial Assets	41	6
Gross Amounts Not Offset, Financial Instruments, Total Derivatives, Financial Assets	(41)	(6)
Gross Amount Not Offset Collateral, Derivatives, Financial Assets	0	0
Net Amount, Derivatives, Financial Assets	0	0
Net Amount Recognized, Derivatives, Financial Liabilities	1,726	3,870
Gross Amounts Not Offset Financial Instruments, Total Derivatives, Financial Liabilities	(41)	(6)
Gross Amounts Not Offset Collateral, Derivatives, Financial Liabilities	(1,571)	(3,864)
Net Amount, Derivatives, Financial Liabilities	114	0
Counterparty B [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Net Amount Recognized, Derivatives, Financial Assets	25,962	7,655
Gross Amounts Not Offset, Financial Instruments, Total Derivatives, Financial Assets	(25,962)	(7,655)
Gross Amount Not Offset Collateral, Derivatives, Financial Assets	0	0
Net Amount, Derivatives, Financial Assets	0	0
Net Amount Recognized, Derivatives, Financial Liabilities	50,901	28,130
Gross Amounts Not Offset Financial Instruments, Total Derivatives, Financial Liabilities	(25,962)	(7,655)
Gross Amounts Not Offset Collateral, Derivatives, Financial Liabilities	(24,939)	(20,475)
Net Amount, Derivatives, Financial Liabilities	0	0
Counterparty C [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Net Amount Recognized, Derivatives, Financial Assets	16
Gross Amounts Not Offset, Financial Instruments, Total Derivatives, Financial Assets	(16)
Gross Amount Not Offset Collateral, Derivatives, Financial Assets	0
Net Amount, Derivatives, Financial Assets	0
Net Amount Recognized, Derivatives, Financial Liabilities	174	9
Gross Amounts Not Offset Financial Instruments, Total Derivatives, Financial Liabilities	(16)	0
Gross Amounts Not Offset Collateral, Derivatives, Financial Liabilities	(10)	(9)
Net Amount, Derivatives, Financial Liabilities	148	0
Other Counterparties [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Net Amount Recognized, Derivatives, Financial Assets	35,975	15,678
Gross Amounts Not Offset, Financial Instruments, Total Derivatives, Financial Assets	(25,533)	(15,678)
Gross Amount Not Offset Collateral, Derivatives, Financial Assets	(10,442)	0
Net Amount, Derivatives, Financial Assets	0	0
Net Amount Recognized, Derivatives, Financial Liabilities	170,013	82,010
Gross Amounts Not Offset Financial Instruments, Total Derivatives, Financial Liabilities	(25,533)	(15,678)
Gross Amounts Not Offset Collateral, Derivatives, Financial Liabilities	(144,463)	(66,225)
Net Amount, Derivatives, Financial Liabilities	$ 17	$ 107