Disclosures About Fair Value of Financial Instruments - Statement of Changes in Level 3 Assets Measured at Fair Value on a Recurring Basis (Detail) - Significant Unobservable Inputs (Level 3) - Asset-backed securities - Fair Value, Measurements, Recurring - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at beginning of period	$ 63,376	$ 121,853	$ 73,266	$ 142,885
Principal payments and premium amortization	(10,444)	(18,147)	(21,660)	(34,496)
Increase in allowance for credit losses	(773)	0	(1,046)	(411)
Decrease in allowance for credit losses	0	317	61	0
Change in fair value recognized in OCI	(334)	2,896	1,204	(1,059)
Balance at end of period	$ 51,825	$ 106,919	$ 51,825	$ 106,919