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	Jun. 30, 2013	Dec. 31, 2012
Variable Interest Entity [Line Items]
Variable Interests Held Classified as Assets	$ 1,799	$ 2,117
Variable Interests Held Classified as Liabilities	71	154
Total Assets in Unconsolidated VIEs	22,598	23,159
Maximum Exposure to Loss	9,666	9,105
Asset-backed commercial paper conduits [Member]
Variable Interest Entity [Line Items]
Variable Interests Held Classified as Assets	0	0
Variable Interests Held Classified as Liabilities	0	0
Total Assets in Unconsolidated VIEs	16,198	16,104
Maximum Exposure to Loss	3,438	2,212
Structured note vehicles [Member]
Variable Interest Entity [Line Items]
Variable Interests Held Classified as Assets	1,799	2,117
Variable Interests Held Classified as Liabilities	71	154
Total Assets in Unconsolidated VIEs	6,400	7,055
Maximum Exposure to Loss	$ 6,228	$ 6,893