Changes in Accumulated Other Comprehensive Income Level 4 (Details) - Reclassifications Out of Accumulated Other Comprehensive Income (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Income tax (benefit) expense	$ 6	$ 4	$ (26)	$ 2
Amounts reclassified from Accumulated other comprehensive loss, net of tax	5	1	10	1
Gains and Losses on Cash Flow Hedges [Member]
Amount Reclassified From Accumulated Other Comprehensive Loss, before tax	0	1	0	1
Income tax (benefit) expense	0	0	1	0
Amounts reclassified from Accumulated other comprehensive loss, net of tax	0	1	1	1
Defined Benefit Pension Items [Member]
Amortization of prior service cost (benefit)	1	0	1	0
Amortization of Actuarial Losses	5	0	9	0
Income tax (benefit) expense	(1)	0	(1)	0
Amounts reclassified from Accumulated other comprehensive loss, net of tax	$ 5	$ 0	$ 9	$ 0