Certain Transfers of Financial Assets and Variable Interest Entities Tax Credit Variable Interest Entities (Details) - USD ($) $ in Millions		Jun. 30, 2018	Dec. 31, 2017
Other Assets	[1]	$ 8,792	$ 9,418
Community Development Investments [Member]
Other Assets	[2]	1,421	1,272
Community Development Investments [Member] | Limited Partner [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	[3]	2,029	1,905
Renewable Energy Program [Member]
Other Assets		13	0
Renewable Energy Program [Member] | Limited Partner [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	[3]	$ 192	$ 0

[1] Beginning January 1, 2018, the Company reclassified equity securities previously presented in Securities available for sale to Other assets. Reclassifications have been made to previously reported amounts for comparability.

[2] At June 30, 2018 and December 31, 2017, the carrying value of community development investments excludes $64 million and $59 million of investments in funds that do not qualify for tax credits, respectively.

[3] At June 30, 2018 and December 31, 2017, community development investment maximum exposure includes $386 million and $354 million of loans and $628 million and $627 million of unfunded equity commitments issued by the Company to these investments, respectively. At June 30, 2018 and December 31, 2017, renewable energy partnership maximum exposure includes $179 million and $0 of unfunded equity commitments issued by the Company to these investments, respectively.