Derivative Financial Instruments and Risk Management (Details 3) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Derivative [Line Items]
Balance at beginning of period, net of tax			$ (6)	$ (14)
Gains (losses) deferred, net of tax	(1)	(1)	(1)	(1)
(Gains) losses reclassified to earnings, net of tax	0	4	1	9
Balance at end of period, net of tax	(6)	(6)	(6)	(6)
Beginning balance, tax			(3)	(6)
Gains (losses) deferred, tax	(1)	0	(1)	0
(Gains) losses reclassified to earnings, tax	1	2	1	3
Ending balance, tax	$ (3)	$ (3)	$ (3)	$ (3)