Stockholders' Equity - Basel III Minimum Capital Adequacy Requirements after Full Phase In (Details)	Dec. 31, 2020		Dec. 31, 2019
Basel III Minimum for Capital Adequacy Purposes
Total Capital to RWA	0.0800	[1]	0.0800
Tier 1 Capital to RWA	0.0600	[1]	0.0600
Tier 1 Capital to AA, or Leverage Ratio	0.0400	[1]	0.0400
Common equity tier 1 capital to RWA	4.50%	[1]	4.50%
Basel III Additional Capital Conservation Buffer
Basel III additional capital conservation buffer at full phase-in	2.50%		2.50%
Basel III "Adequate" Ratio with Capital Conservation Buffer
Total Capital to RWA	10.50%
Tier 1 Capital to RWA	8.50%
Tier 1 Capital to AA, or Leverage Ratio	4.00%
Common equity tier 1 capital to RWA	7.00%

[1] Before application of the capital conservation buffer of 2.50% as of December 31, 2020 and December 31, 2019. See discussion below.