Certain Transfers of Financial Assets and Variable Interest Entities Tax Credit Variable Interest Entities (Details) - USD ($) $ in Millions		Mar. 31, 2019	Dec. 31, 2018
Other Assets		$ 10,719	$ 8,991
Community Development Investments [Member]
Other Assets	[1]	1,686	1,636
Community Development Investments [Member] | Limited Partner [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	[2]	2,262	2,207
Renewable Energy Program [Member]
Other Assets		81	86
Renewable Energy Program [Member] | Limited Partner [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	[2]	$ 81	$ 138

[1] At March 31, 2019 and December 31, 2018, the carrying value of community development investments excludes $69 million and $68 million of investments in funds that do not qualify for tax credits, respectively.

[2] At March 31, 2019 and December 31, 2018, the Company's maximum exposure to loss related to community development investments includes $503 million and $422 million of loans and $579 million and $639 million of unfunded equity commitments, respectively. At March 31, 2019 and December 31, 2018, the Company's maximum exposure to loss related to renewable energy partnerships includes $0 and $52 million of unfunded equity commitments, respectively.