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	Mar. 31, 2015	Dec. 31, 2014
Variable Interest Entity [Line Items]
Variable Interest Held Classified as Assets	$ 2,942	$ 2,914
Variable Interests Held Classified as Liabilities	45	46
Total Assets in Unconsolidated VIEs	16,778	16,992
Maximum Exposure to Loss	8,622	8,589
Asset-backed commercial paper conduits [Member]
Variable Interest Entity [Line Items]
Variable Interest Held Classified as Assets	50	29
Variable Interests Held Classified as Liabilities	0	0
Total Assets in Unconsolidated VIEs	10,761	10,984
Maximum Exposure to Loss	2,710	2,685
Structured note vehicles [Member]
Variable Interest Entity [Line Items]
Variable Interest Held Classified as Assets	2,848	2,841
Variable Interests Held Classified as Liabilities	7	7
Total Assets in Unconsolidated VIEs	5,876	5,867
Maximum Exposure to Loss	5,868	5,860
Low income housing partnerships [Member]
Variable Interest Entity [Line Items]
Variable Interest Held Classified as Assets	44	44
Variable Interests Held Classified as Liabilities	38	39
Total Assets in Unconsolidated VIEs	141	141
Maximum Exposure to Loss	$ 44	$ 44