Fair Value Fair Value (Details 2) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Fair Value Transfers Between Level 1, Level 2 and Level 3 [Line Items]
Transfers from Level 2 to Level 1	$ 0	$ 0	$ 0	$ 0
Transfers from Level 3 to Level 1	0	0	0	0
Transfers from Level 1 to Level 2	0	0	0	0
Transfers from Level 3 to Level 2	1	0	2	2
Transfers from Level 1 to Level 3	0	0	0	0
Transfers from Level 2 to Level 3	$ 0	$ 0	$ 0	$ 29