Variable Interest Entities - Variable Interests Held by Us and Our Maximum Exposure to Loss Rising From Our Involvements in Those VIEs (Details) - USD ($) $ in Millions	Sep. 30, 2015	Dec. 31, 2014
Variable Interest Entity [Line Items]
Variable Interest Held Classified as Assets	$ 3,038	$ 2,914
Variable Interests Held Classified as Liabilities	89	46
Total Assets in Unconsolidated VIEs	17,461	16,992
Maximum Exposure to Loss	9,073	8,589
Asset-backed commercial paper conduits [Member]
Variable Interest Entity [Line Items]
Variable Interest Held Classified as Assets	85	29
Variable Interests Held Classified as Liabilities	0	0
Total Assets in Unconsolidated VIEs	11,273	10,984
Maximum Exposure to Loss	3,097	2,685
Structured note vehicles [Member]
Variable Interest Entity [Line Items]
Variable Interest Held Classified as Assets	2,863	2,841
Variable Interests Held Classified as Liabilities	8	7
Total Assets in Unconsolidated VIEs	5,894	5,867
Maximum Exposure to Loss	5,886	5,860
Low income housing partnerships [Member]
Variable Interest Entity [Line Items]
Variable Interest Held Classified as Assets	90	44
Variable Interests Held Classified as Liabilities	81	39
Total Assets in Unconsolidated VIEs	294	141
Maximum Exposure to Loss	$ 90	$ 44