Long-Term Debt (Committed Funding Facilities) (Details) (Committed Funding Facilities [Member], USD $) In Millions, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Debt Instrument [Line Items]
Outstanding	$ 18,892	$ 17,909
Unused capacity	5,641	6,747
Total capacity	24,533	24,656
Bank Funding Member | Secured Debt [Member]
Debt Instrument [Line Items]
Outstanding	2,500	2,750
Unused capacity	1,000	250
Total capacity	3,500	3,000
Nonbank Funding [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Outstanding	16,392	15,159
Unused capacity	4,641	6,497
Total capacity	21,033	21,656
Revolving secured funding facilities [Member]
Debt Instrument [Line Items]
Total capacity	22,400
Revolving secured funding facilities 1 year or greater [Member]
Debt Instrument [Line Items]
Total capacity	$ 15,500