Derivative Financial Instruments and Risk Management (Details 3) (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
Balance at beginning of period, net of tax			$ (8)	$ (6)
Gains (losses) deferred during the period, net of tax	2	(1)	2	(1)
(Gains) losses reclassified to earnings, net of tax	1	0	2	1
Balance at end of period, net of tax	(4)	(6)	(4)	(6)
Beginning balance, tax			4	3
Gains (losses) deferred during the period, tax	(1)	1	(1)	1
(Gains) losses reclassified to earnings, tax	1	1	1	1
Ending balance, tax	$ 2	$ 3	$ 2	$ 3