Other Assets Low-Income Housing Partnership (Details) - USD ($) $ in Millions	1 Months Ended	12 Months Ended
	Jul. 31, 2010	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Variable Interest Entity, Not Primary Beneficiary
Variable Interest Entity [Line Items]
Company limited partner holding interest, percentage	99.90%
Tax Credits, reduction to income tax expense		$ 20	$ 8	$ 39
Unamortized investment balance classified as Other Assets		51	118
Maximum exposure to loss		$ 51	$ 118
Variable Interest Entity, Primary Beneficiary
Variable Interest Entity [Line Items]
General partner holding interest, percentage	0.10%