Regulatory Matters - Summary of Required Minimum and Well Capitalized Capital Ratios (Detail)	Dec. 31, 2020
Regulatory Capital Requirements [Abstract]
Common equity Tier 1 ("CET1") to risk-weighted assets, Minimum	4.50%
Tier 1 capital to risk-weighted assets, Minimum	0.060
Total capital to risk-weighted assets, Minimum	0.080
Leverage — Tier 1 capital to average total assets, as defined	0.040
Common equity Tier 1 ("CET1") to risk-weighted assets, Well Capitalized	6.50%
Tier 1 capital to risk-weighted assets, Well capitalized	0.080
Total capital to risk-weighted assets, Well capitalized	0.100
Leverage — Tier 1 capital to average total assets, as defined	0.050