Derivatives (Details) (Not designated as hedging instruments, USD $) In Millions, except Share data, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Interest rate lock commitments
Notional amount of derivatives
Notional	$ 1,982	$ 4,993
Forward delivery commitments
Notional amount of derivatives
Notional	6,539	12,303
Option contracts
Notional amount of derivatives
Notional	610	1,070
Interest rate contracts
Notional amount of derivatives
Notional	715	614
MSR-related agreements
Notional amount of derivatives
Notional		$ 3,915
Convertible note-related agreements | Common stock
Notional amount of derivatives
Notional amount (in shares)	9,688,100	9,688,100