Goodwill and Intangible Assets - Components (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Schedule of Intangible Assets by Major Class [Line Items]
Goodwill, gross	$ 14,653	$ 14,653
Goodwill	14,653	14,653	$ 14,544	$ 14,533
Intangible assets, gross (excluding Goodwill)	396	2,178
Accumulated amortization	(306)	(2,004)
Intangible assets, net (excluding Goodwill)	$ 90	$ 174
Finite-Lived Intangible Assets, Remaining Amortization Period	7 years 1 month 6 days	5 years 7 months 6 days
Intangible assets gross including Goodwill	$ 15,049	$ 16,831
Total goodwill and other intangible assets, net carrying value	14,743	14,827
Commercial MSRs, gross	542	555
Commercial MSR, accumulated amortization	(175)	(255)
Total commercial MSRs	367	300
Amortization expense for amortizable intangible assets	69	70
PCCR intangibles
Schedule of Intangible Assets by Major Class [Line Items]
Intangible assets, gross (excluding Goodwill)	148	1,932
Accumulated amortization	(138)	(1,864)
Intangible assets, net (excluding Goodwill)	$ 10	$ 68
Finite-Lived Intangible Assets, Remaining Amortization Period	6 years 2 months 12 days	3 years 10 months 24 days
Other intangible assets
Schedule of Intangible Assets by Major Class [Line Items]
Intangible assets, gross (excluding Goodwill)	$ 248	$ 246
Accumulated amortization	(168)	(140)
Intangible assets, net (excluding Goodwill)	$ 80	$ 106
Finite-Lived Intangible Assets, Remaining Amortization Period	7 years 3 months 18 days	6 years 8 months 12 days