Regulatory Requirements - U.S. Bank Subsidiaries' Regulatory Capital and Capital Ratios (Details) $ in Millions	Mar. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)
Required Ratio
Common Equity Tier 1 capital (as a percent)	13.20%	13.20%
Tier 1 capital (as a percent)	0.147	0.147
Total capital (as a percent)	0.167	0.167
Tier 1 leverage (as a percent)	0.040
SLR (as a percent)	5.00%
Amount
Common Equity Tier 1 capital	$ 72,477	$ 75,742
Tier 1 capital	80,121	83,348
Total capital	$ 89,468	$ 93,166
Ratio
Common Equity Tier 1 capital (as a percent)	0.145	0.160
Tier 1 capital (as a percent)	0.160	0.177
Total capital (as a percent)	0.178	0.197
Tier 1 leverage (as a percent)	0.068	0.071
SLR (as a percent)	0.055	0.056
MSBNA
Well-Capitalized Requirement Ratio [Abstract]
Common Equity Tier 1 capital (as a percent)	6.50%
Tier 1 capital (as a percent)	8.00%
Total capital (as a percent)	0.100
Tier 1 leverage (as a percent)	0.050
SLR (as a percent)	6.00%
Required Ratio
Common Equity Tier 1 capital (as a percent)	7.00%
Tier 1 capital (as a percent)	0.085
Total capital (as a percent)	0.105
Tier 1 leverage (as a percent)	0.040
SLR (as a percent)	3.00%
Amount
Common Equity Tier 1 capital	$ 18,386	$ 18,960
Tier 1 capital	18,386	18,960
Total capital	18,961	19,544
Tier 1 leverage	18,386	18,960
SLR	$ 18,386	$ 18,960
Ratio
Common Equity Tier 1 capital (as a percent)	0.187	0.205
Tier 1 capital (as a percent)	0.187	0.205
Total capital (as a percent)	0.193	0.211
Tier 1 leverage (as a percent)	0.093	0.102
SLR (as a percent)	0.074	0.081
MSPBNA
Well-Capitalized Requirement Ratio [Abstract]
Common Equity Tier 1 capital (as a percent)	6.50%
Tier 1 capital (as a percent)	8.00%
Total capital (as a percent)	0.100
Tier 1 leverage (as a percent)	0.050
SLR (as a percent)	6.00%
Required Ratio
Common Equity Tier 1 capital (as a percent)	7.00%
Tier 1 capital (as a percent)	0.085
Total capital (as a percent)	0.105
Tier 1 leverage (as a percent)	0.040
SLR (as a percent)	3.00%
Amount
Common Equity Tier 1 capital	$ 15,142	$ 10,293
Tier 1 capital	15,142	10,293
Total capital	15,237	10,368
Tier 1 leverage	15,142	10,293
SLR	$ 15,142	$ 10,293
Ratio
Common Equity Tier 1 capital (as a percent)	0.294	0.243
Tier 1 capital (as a percent)	0.294	0.243
Total capital (as a percent)	0.296	0.245
Tier 1 leverage (as a percent)	0.074	0.069
SLR (as a percent)	0.073	0.067