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	Dec. 31, 2015	Dec. 31, 2014
Variable Interest Entity [Line Items]
Variable Interest Held Classified as Assets	$ 3,066	$ 2,914
Variable Interests Held Classified as Liabilities	129	46
Total Assets in Unconsolidated VIEs	21,373	16,992
Maximum Exposure to Loss	9,379	8,589
Asset-backed commercial paper conduits [Member]
Variable Interest Entity [Line Items]
Variable Interest Held Classified as Assets	58	29
Variable Interests Held Classified as Liabilities	0	0
Total Assets in Unconsolidated VIEs	15,183	10,984
Maximum Exposure to Loss	3,362	2,685
Structured note vehicles [Member]
Variable Interest Entity [Line Items]
Variable Interest Held Classified as Assets	2,870	2,841
Variable Interests Held Classified as Liabilities	8	7
Total Assets in Unconsolidated VIEs	5,888	5,867
Maximum Exposure to Loss	5,879	5,860
Low income housing partnerships [Member]
Variable Interest Entity [Line Items]
Variable Interest Held Classified as Assets	138	44
Variable Interests Held Classified as Liabilities	121	39
Total Assets in Unconsolidated VIEs	302	141
Maximum Exposure to Loss	$ 138	$ 44