Derivatives (Details 2) (USD $) In Millions, unless otherwise specified	3 Months Ended				6 Months Ended
	Jun. 30, 2013		Jun. 30, 2012		Jun. 30, 2013		Jun. 30, 2012
Net After-tax Derivative Activity recorded in AOCI
Beginning balance-AOCI	$ (17)		$ (13)		$ (7)		$ 1
Unrealized gains (losses) recognized in AOCI	7	[1]	(2)	[1]	1	[1]	12	[1]
Losses reclassified to income	1	[2]	4	[2]	(3)	[2]	(24)	[2]
Ending balance - AOCI	$ (9)		$ (11)		$ (9)		$ (11)

[1] Net of tax of $(4) and zero for the three months ended June 30, 2013 and 2012, respectively, and $(1) and $(8) for the six months ended June 30, 2013 and 2012.

[2] Net of tax of zero and $(2) for the three months ended June 30, 2013 and 2012, respectively, and $2 and $15 for the six months ended June 30, 2013 and 2012.