Regulatory Capital Requirements - Capital Conservation Buffer (Details)	Dec. 31, 2019	Jan. 01, 2019	Dec. 31, 2018	Jan. 01, 2016
Regulatory Capital Requirements
Phased in rate (as a percent)				0.625%
Annual increase after initial year (as a percent)	0.625%
Capital requirements above regulatory rate (as a percent)		2.50%
Effective CET1 capital to risk-weighted assets (as a percent)	4.50%		4.50%
Effective Tier 1 capital to risk-weighted assets (as a percent)	11.88%		11.97%
Effective total capital to risk-weighted assets (as a percent)	12.81%		12.99%