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, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Variable Interest Entity [Line Items]
Variable Interest Held Classified as Assets	$ 2,914	$ 2,689
Variable Interests Held Classified as Liabilities	46	55
Total Assets in Unconsolidated VIEs	16,992	23,234
Maximum Exposure to Loss	8,589	8,448
Asset-backed commercial paper conduits [Member]
Variable Interest Entity [Line Items]
Variable Interest Held Classified as Assets	29	417
Variable Interests Held Classified as Liabilities	0	0
Total Assets in Unconsolidated VIEs	10,984	17,044
Maximum Exposure to Loss	2,685	2,560
Structured note vehicles [Member]
Variable Interest Entity [Line Items]
Variable Interest Held Classified as Assets	2,841	2,272
Variable Interests Held Classified as Liabilities	7	55
Total Assets in Unconsolidated VIEs	5,867	6,190
Maximum Exposure to Loss	5,860	5,888
Low income housing partnerships [Member]
Variable Interest Entity [Line Items]
Variable Interest Held Classified as Assets	44
Variable Interests Held Classified as Liabilities	39
Total Assets in Unconsolidated VIEs	141
Maximum Exposure to Loss	$ 44