Debt (Details) (USD $)																															12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2012 Term loans	Dec. 31, 2011 Term loans	Dec. 31, 2012 Notes due 2012	Dec. 31, 2011 Notes due 2012	Dec. 31, 2012 Notes due 2013	Dec. 31, 2011 Notes due 2013	Dec. 31, 2012 Notes due 2014		Dec. 31, 2011 Notes due 2014		Dec. 31, 2012 Notes due 2015	Dec. 31, 2011 Notes due 2015	Dec. 31, 2012 Notes due 2016	Dec. 31, 2011 Notes due 2016	Dec. 31, 2012 Notes due 2017	Dec. 31, 2011 Notes due 2017	Dec. 31, 2012 Notes due 2019	Dec. 31, 2011 Notes due 2019	Dec. 31, 2012 Notes due 2022		Dec. 31, 2011 Notes due 2022		Dec. 31, 2012 Notes due 2037		Dec. 31, 2011 Notes due 2037		Dec. 31, 2012 Interest Rate Swap 450M	Dec. 31, 2012 Prime Rate	Dec. 31, 2012 Prime Rate Notes due 2018	Dec. 31, 2011 Prime Rate Notes due 2018	Dec. 31, 2012 LIBOR	Dec. 31, 2012 LIBOR Notes due 2018	Dec. 31, 2011 LIBOR Notes due 2018
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage							4.625%		3.875%		4.875%				5.00%		4.75%		5.75%		6.25%		5.25%				5.25%						4.75%			5.60%
Debt Instrument, Face Amount					$ 230,000,000	$ 150,000,000	$ 0	$ 400,000,000	$ 375,000,000	$ 375,000,000	$ 450,000,000	[1]	$ 450,000,000	[1]	$ 400,000,000	$ 400,000,000	$ 500,000,000	$ 500,000,000	$ 500,000,000	$ 500,000,000	$ 300,000,000	$ 300,000,000	$ 110,000,000	[2]	$ 0	[2]	$ 500,000,000	[3]	$ 500,000,000	[3]			$ 350,000,000	$ 350,000,000		$ 250,000,000	$ 250,000,000
Debt Instrument, Unamortized Discount (Premium), Net	52,375,000	[4]	58,909,000	[4]
Total Debt	4,017,375,000		4,233,909,000
Debt, Current	375,000,000		550,000,000
Long-term Debt, Current Maturities	3,642,375,000		3,683,909,000
Debt Instrument, Basis Spread on Variable Rate																																1.25%			2.25%
Derivative, Notional Amount	450,000,000
Derivative, Description of Variable Rate Basis																															three-month LIBOR
Derivative, Basis Spread on Variable Rate	30500.00%
Derivative, Fixed Interest Rate	4.875%
Debt, Weighted Average Interest Rate			3.50%
Maturities of Long-term Debt [Abstract]
2013	375,000,000
2014	450,000,000
2015	450,000,000
2016	680,000,000
2017	500,000,000
Thereafter	1,510,000,000
Total	3,965,000,000
Line of Credit Facility, Remaining Borrowing Capacity	$ 1,000,000,000

[1] We have interest rate swap agreements with an aggregate notional value of $450 million that effectively convert the fixed rate interest payments on this debt issue into variable interest rates. We pay a weighted-average variable rate based on three-month LIBOR plus 305 basis points and receive a fixed rate of 4.875%. The weighted-average rate paid during 2012 and 2011 was 3.5%.

[2] In November 2012, we issued $110 million of 10-year notes with a coupon rate of 5.25%. Interest is paid quarterly beginning February 2013. The notes mature on November 27, 2022; however, we may redeem some or all of the notes at anytime on or after November 27, 2015 at a redemption price equal to 100% of the principal amount, plus accrued and unpaid interest. The proceeds from the notes will be used for general corporate purposes, including the repayment of 2013 debt maturities.

[3] Under the terms of these notes, in January 2017, bondholders may redeem the notes, in whole or in part, at par plus accrued interest.

[4] Other consists of the unamortized net proceeds received from unwinding of interest rate swaps, the mark-to-market adjustment of interest rate swaps and debt discounts and premiums.