Regulatory Capital Requirements (Details)	3 Months Ended
	Mar. 31, 2020	Dec. 31, 2019
Regulatory Capital Requirements
Common Equity Tier 1 Capital (to risk weighted assets), ratio (as a percent)	11.70%	11.70%
Tier 1 Capital (to risk weighted assets), ratio (as a percent)	11.70%	11.70%
Total Capital (to risk weighted assets), ratio (as a percent)	13.10%	13.10%
Tier 1 Leverage ratio (as a percent)	9.60%	11.90%
Minimum | FDIC
Regulatory Capital Requirements
Common Equity Tier 1 Capital (to risk weighted assets), ratio (as a percent)	4.50%
Tier 1 Capital (to risk weighted assets), ratio (as a percent)	6.00%
Total Capital (to risk weighted assets), ratio (as a percent)	8.00%
Tier 1 Leverage ratio (as a percent)	4.00%
Basel III Capital Rules | FDIC
Regulatory Capital Requirements
Capital conservation buffer ratio	2.50%
Capital conservation buffer ratio annual increment during phase-in period	0.625%
Implementation period of capital conservation buffer requirement	4 years
Basel III Capital Rules | Minimum | FDIC
Regulatory Capital Requirements
Common Equity Tier 1 Capital (to risk weighted assets), ratio (as a percent)	7.00%
Tier 1 Capital (to risk weighted assets), ratio (as a percent)	8.50%
Total Capital (to risk weighted assets), ratio (as a percent)	10.50%