Regulatory Matters - Additional Information (Detail)	Dec. 31, 2019	Mar. 31, 2018	Dec. 31, 2017
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Increase in risk-based capital ratios		0.625%
Basel III Phase-in Schedule [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Minimum capital level requirements, Total capital ratio		1.875%	1.25%
Scenario, Forecast [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Minimum capital level requirements, Total capital ratio	10.50%
Minimum capital level requirements, Tier 1 capital ratio	8.50%
Scenario, Forecast [Member] | Common Stock [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Minimum capital level requirements, Tier 1 capital ratio	7.00%