Other Assets (Details) - USD ($) $ in Millions	1 Months Ended	9 Months Ended
	Jul. 31, 2010	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Variable Interest Entity, Not Primary Beneficiary
Variable Interest Entity [Line Items]
Company limited partner holding interest, percentage	99.90%
Variable Interest Entity, Assets		$ 325		$ 355
Affordable Housing Tax Credits and Other Tax Benefits, Amount		27	$ 28
Unamortized investment balance classified as Other Assets		282		314
Other Commitment		0		18
Maximum exposure to loss		$ 282		$ 314
Variable Interest Entity, Primary Beneficiary
Variable Interest Entity [Line Items]
General partner holding interest, percentage	0.10%