Long-Term Debt (Committed Funding Facilities) (Details) - Committed Funding Facilities [Member] - USD ($) $ in Millions	Sep. 30, 2015	Dec. 31, 2014
Debt Instrument [Line Items]
Outstanding	$ 20,169	$ 18,280
Unused capacity	1,491	3,675
Total capacity	21,660	21,955
Bank Funding Member | Secured Debt [Member]
Debt Instrument [Line Items]
Outstanding	3,015	3,250
Unused capacity	235	250
Total capacity	3,250	3,500
Nonbank Funding [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Outstanding	17,154	15,030
Unused capacity	1,256	3,425
Total capacity	18,410	$ 18,455
Revolving secured funding facilities [Member]
Debt Instrument [Line Items]
Total capacity	21,200
Revolving secured funding facilities 1 year or greater [Member]
Debt Instrument [Line Items]
Total capacity	$ 17,400