Regulatory Matters (Details) $ in Millions	Jun. 30, 2022 USD ($)	Dec. 31, 2021 USD ($)
Tier 1 capital (to adjusted avg. total assets)
Tier 1 capital actual amount	$ 2,900	$ 2,798
Tier 1 capital (to adjusted tangible assets), actual ratio	0.1217	0.1054
Tier 1 capital, for capital adequacy purposes amount	$ 953	$ 1,062
Tier 1 capital (to adjusted tangible assets), for capital adequacy purposes ratio	0.040	0.040
Tier 1 capital capitalized under prompt corrective action provision amount	$ 1,192	$ 1,327
Tier 1 capital (to adjusted tangible assets), capitalized under prompt corrective action provision ratio	0.050	0.050
Common equity Tier 1 capital (to RWA)
Common equity Tier 1 capital (to RWA), actual amount	$ 2,660	$ 2,558
Common equity Tier 1 capital (to RWA), actual ratio	13.22%	13.19%
Common equity Tier 1 capital (to RWA), for capital adequacy purposes, amount	$ 906	$ 873
Common equity Tier 1 capital (to RWA), for capital adequacy purposes, ratio	4.50%	4.50%
Common equity Tier 1 capital (to RWA), well capitalized under prompt corrective action provisions, amount	$ 1,308	$ 1,261
Common equity Tier 1 capital (to RWA), well capitalized under prompt corrective action provisions, ratio	6.50%	6.50%
Tier 1 capital (to RWA)
Tier 1 capital, actual amount	$ 2,900	$ 2,798
Tier 1 capital (to risk-weighted assets), actual ratio	0.1441	0.1443
Tier 1 capital, for capital adequacy purposes amount	$ 1,208	$ 1,164
Tier 1 capital (to risk-weighted assets), for capital adequacy purposes ratio	0.060	0.060
Tier 1 capital, capitalized under prompt corrective action provision amount	$ 1,610	$ 1,552
Tier 1 capital (to risk-weighted assets), capitalized under prompt corrective action provision ratio	0.080	0.080
Total capital (to RWA)
Total capital, actual amount	$ 3,155	$ 3,080
Total capital (to risk-weighted assets), actual ratio	0.1568	0.1588
Total capital, for capital adequacy purposes amount	$ 1,610	$ 1,552
Total capital (to risk-weighted assets), for capital adequacy purposes ratio	0.080	0.080
Total capital, capitalized under prompt corrective action provisions amount	$ 2,013	$ 1,940
Total capital (to risk-weighted assets), capitalized under prompt corrective action provisions ratio	0.100	0.100
Bank
Tier 1 capital (to adjusted avg. total assets)
Tier 1 capital actual amount	$ 2,824	$ 2,706
Tier 1 capital (to adjusted tangible assets), actual ratio	0.1187	0.1021
Tier 1 capital, for capital adequacy purposes amount	$ 951	$ 1,060
Tier 1 capital (to adjusted tangible assets), for capital adequacy purposes ratio	0.040	0.040
Tier 1 capital capitalized under prompt corrective action provision amount	$ 1,189	$ 1,325
Tier 1 capital (to adjusted tangible assets), capitalized under prompt corrective action provision ratio	0.050	0.050
Common equity Tier 1 capital (to RWA)
Common equity Tier 1 capital (to RWA), actual amount	$ 2,824	$ 2,706
Common equity Tier 1 capital (to RWA), actual ratio	14.04%	13.96%
Common equity Tier 1 capital (to RWA), for capital adequacy purposes, amount	$ 905	$ 872
Common equity Tier 1 capital (to RWA), for capital adequacy purposes, ratio	4.50%	4.50%
Common equity Tier 1 capital (to RWA), well capitalized under prompt corrective action provisions, amount	$ 1,307	$ 1,260
Common equity Tier 1 capital (to RWA), well capitalized under prompt corrective action provisions, ratio	6.50%	6.50%
Tier 1 capital (to RWA)
Tier 1 capital, actual amount	$ 2,824	$ 2,706
Tier 1 capital (to risk-weighted assets), actual ratio	0.1404	0.1396
Tier 1 capital, for capital adequacy purposes amount	$ 1,207	$ 1,163
Tier 1 capital (to risk-weighted assets), for capital adequacy purposes ratio	0.060	0.060
Tier 1 capital, capitalized under prompt corrective action provision amount	$ 1,609	$ 1,551
Tier 1 capital (to risk-weighted assets), capitalized under prompt corrective action provision ratio	0.080	0.080
Total capital (to RWA)
Total capital, actual amount	$ 2,931	$ 2,839
Total capital (to risk-weighted assets), actual ratio	0.1457	0.1465
Total capital, for capital adequacy purposes amount	$ 1,609	$ 1,551
Total capital (to risk-weighted assets), for capital adequacy purposes ratio	0.080	0.080
Total capital, capitalized under prompt corrective action provisions amount	$ 2,011	$ 1,938
Total capital (to risk-weighted assets), capitalized under prompt corrective action provisions ratio	0.100	0.100