Debt (Senior Notes) (Narrative) (Details) (USD $)					6 Months Ended			6 Months Ended			6 Months Ended											6 Months Ended	12 Months Ended	6 Months Ended
	Jun. 30, 2013	Dec. 31, 2012	Jun. 30, 2013 Interest rate swaps 2016 Senior Notes	Jun. 30, 2013 Interest rate swaps 2018 - 6.0% Senior Notes	Jun. 30, 2013 Senior Notes 2016 Senior Notes	Jun. 18, 2013 Senior Notes 2016 Senior Notes	Dec. 31, 2012 Senior Notes 2016 Senior Notes	Jun. 30, 2013 Senior Notes 2018 - 2.6% Senior Notes	Jun. 18, 2013 Senior Notes 2018 - 2.6% Senior Notes	Dec. 31, 2012 Senior Notes 2018 - 2.6% Senior Notes	Jun. 30, 2013 Senior Notes 2017 Senior Notes		Dec. 31, 2012 Senior Notes 2017 Senior Notes	May 12, 2010 Senior Notes 2017 Senior Notes	Jun. 30, 2013 Senior Notes 2018 - 6.0% Senior Notes	Dec. 31, 2012 Senior Notes 2018 - 6.0% Senior Notes	Nov. 09, 2010 Senior Notes 2018 - 6.0% Senior Notes	Jun. 30, 2013 Senior Notes 2020 Senior Notes	Dec. 31, 2012 Senior Notes 2020 Senior Notes	Jun. 30, 2013 Senior Notes 2023 Senior Notes	Dec. 31, 2012 Senior Notes 2023 Senior Notes	Jun. 30, 2013 Senior Notes Floating-rate debt 2018 - 6.0% Senior Notes	Dec. 31, 2012 Senior Notes Floating-rate debt 2018 - 6.0% Senior Notes	Jun. 30, 2013 Senior Notes Redemption premium 2017 Senior Notes	Jun. 30, 2013 Fixed-rate debt Interest rate swaps	Dec. 31, 2012 Fixed-rate debt Interest rate swaps	Jun. 18, 2013 Fixed-rate debt Interest rate swaps 2016 Senior Notes
Debt Instrument [Line Items]
Long-term debt, gross	$ 5,073,984,000				$ 500,000,000	$ 500,000,000		$ 650,000,000			$ 550,000,000	[1]			$ 800,000,000			$ 1,000,000,000		$ 750,000,000
Debt instrument, interest rate, stated percentage						1.80%			2.60%					7.625%			6.00%
Notional amount of interest rate fair value hedge derivatives																									1,000,000,000	500,000,000	500,000,000
Debt instrument, interest rate at period end			1.45%	3.23%
Long-term debt	5,812,184,000	5,431,948,000		500,000,000	497,047,000		0	648,646,000		0	550,000,000		550,000,000		813,546,000	826,974,000		1,012,700,000	1,013,372,000	748,518,000	748,452,000	813,500,000	827,000,000
Discount on debt					400,000			1,400,000												1,500,000	1,500,000	9,000,000	9,700,000
Equivalent price percentage of principal amount redeemable					100.00%			100.00%
Debt instrument, basis spread on variable rate					0.20%			0.30%
Total redemption amount											608,800,000
Redemption premium											64,000,000													58,800,000
Fair value adjustment					(2,600,000)																	22,500,000	36,600,000
Premium on debt																		$ 12,700,000	$ 13,400,000

[1] The redemption of the 2017 Senior Notes on July 18, 2013 was funded through borrowings under the Revolving Facility and, as such, the amount outstanding at June 30, 2013 is classified as non-current in the Condensed Consolidated Balance Sheets.