Derivative and Hedging Activities Derivative Instruments, Gain/Loss In Statement Of Financial Performance (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) recognized in net income (loss)	$ (50)	$ 7	$ (54)	$ 2
Fair Value Hedging | Interest rate contract | Interest Expense
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) recognized in net income (loss)	$ 1	$ 2	$ 3	$ 4