Income Taxes (Details) (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 Taxes, Tax Rate [Line Items]
Interest Expense Related To Income Taxes	$ 11	$ 9	$ 20	$ 11
Gross interest and penalties recognized in period			$ 30
Effective Income Tax Rate, Continuing Operations, Tax Rate Reconciliation [Abstract]
Effective Income Tax Rate, Continuing Operations	14.30%	1.10%	7.60%	0.90%
Effective Tax Rate	14.70%	14.50%	14.10%	14.70%
Impact of certain receipts charges	0.40%	13.40%	6.50%	13.80%