Long-Term Debt Narrative (Details) (USD $) In Millions, unless otherwise specified			1 Months Ended	9 Months Ended	3 Months Ended			3 Months Ended			3 Months Ended
	Sep. 30, 2013	Dec. 31, 2012	May 31, 2013 Revolving Credit Facility [Member]	Sep. 30, 2013 Revolving Credit Facility [Member]	Sep. 30, 2013 9.375% Senior Notes Due 2016	Apr. 30, 2013 9.375% Senior Notes Due 2016	Sep. 04, 2013 5.75% Senior Notes Due 2020 [Member]	Sep. 30, 2013 5.75% Senior Notes Due 2020 [Member] Redemption Before June 1, 2020 [Member]	Sep. 30, 2013 5.75% Senior Notes Due 2020 [Member] Redemption After June 1, 2020 [Member]	Apr. 30, 2013 4.5% Senior Notes Due Two Thousand Twenty Three [Member]	Sep. 30, 2013 4.5% Senior Notes Due Two Thousand Twenty Three [Member] Redemption Before August 1, 2023	Sep. 30, 2013 4.5% Senior Notes Due Two Thousand Twenty Three [Member] Redemption After August 1, 2023	Sep. 30, 2013 5.75% Senior Notes Due 2020 [Member] 4.5% Senior Notes Due Two Thousand Twenty Three [Member]
Long-term debt weighted-average interest rate				2.19%
Revolving credit facility maximum allowable additional borrowings	$ 1,200	$ 1,150	$ 1,200
Line of Credit Facility, Additional Borrowing Capacity			300
Acquisition threshold amount for an increase in the permitted Total Leverage Ratio for the revolver			50
Write off of Deferred Debt Issuance Cost				1
Deferred Finance Costs, Net				7
Debt Instrument, Face Amount							400			600
Debt Instrument, Interest Rate, Stated Percentage						9.375%	5.75%			4.50%
Senior Note Redemption Percentage								100.00%	100.00%		100.00%	100.00%	101.00%
Indenture Terms, Days of Rating Decline													90
Repayments of Long-term Debt					163
Senior Note Redemption Price					178
Debt Instrument, Increase, Accrued Interest					$ 7