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
	Mar. 31, 2013	Mar. 31, 2012
Income tax (benefit) expense	$ (32)	$ (2)
Amounts reclassified from Accumulated other comprehensive loss, net of tax	5	1
Gains and Losses on Cash Flow Hedges [Member]
Amount Reclassified From Accumulated Other Comprehensive Loss, before tax	0	1
Income tax (benefit) expense	1	0
Amounts reclassified from Accumulated other comprehensive loss, net of tax	1	1
Defined Benefit Pension Items [Member]
Amortization of prior service cost (benefit)	0	0
Amortization of Actuarial Losses	5	0
Income tax (benefit) expense	(1)	0
Amounts reclassified from Accumulated other comprehensive loss, net of tax	$ 4	$ 0