Commitments, Off-Balance Sheet Arrangements, and Contingent Liabilities (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Commitments, Off-Balance Sheet Arrangements, and Contingent Liabilities (Textuals) [Line Items]
Unfunded commitments	$ 24	$ 24
Expense Related to Qualified Affordable Housing Projects	17	8	$ 3
Remaining Investment in Qualified Affordable Housing Projects	132	141
Variable Interest Entity Reporting Entity Involvement Unfunded Obligation Amount	51	93
Loans repurchased under make whole requests	2	1
Loans sold to outside investors original amount	11,100
Loans sold to outside investors remaining outstanding amount	7,300
Residential mortgage loans sold with recourse risk	47	44
Residential mortgage loans sold with credit recourse risk	57	73
UnconsolidatedProjectsLowIncomeHousing [Member]
Commitments, Off-Balance Sheet Arrangements, and Contingent Liabilities (Textuals) [Line Items]
Carrying value of investments	136	147
PrincipalInvestmentCommitment [Member]
Commitments, Off-Balance Sheet Arrangements, and Contingent Liabilities (Textuals) [Line Items]
Carrying value of investments	$ 25	$ 23