Fair Value Disclosures - Summary of Loans Held-for-Sale at Fair Value (Detail) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020	Mar. 31, 2020
Fair Value Measurements Loans Held For Sale [Abstract]
Unpaid principal balance on loans held-for-sale	$ 60,727	$ 76,602	$ 38,563
Net unrealized gains on loans held-for-sale	784	2,983	1,096
Loans held-for-sale at fair value	$ 61,511	$ 79,585	$ 39,659