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) - Residential Mortgage Loan Commitments - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at beginning of period	$ 215	$ 77	$ 79	$ 69
Issuances	52	145	267	222
Settlements	(215)	(77)	(294)	(146)
Balance at end of period	$ 52	$ 145	$ 52	$ 145