Long-term Debt (Details) (USD $)	12 Months Ended																							12 Months Ended		12 Months Ended		12 Months Ended		12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Dec. 31, 2011 Debt Due 2012 [Member]	Dec. 31, 2010 Debt Due 2012 [Member]	Dec. 31, 2011 Debt Due 2013 [Member]	Dec. 31, 2010 Debt Due 2013 [Member]	Dec. 31, 2011 Debt Due 2014 [Member]	Dec. 31, 2010 Debt Due 2014 [Member]	Dec. 31, 2011 Debt Due 2015 [Member]	Dec. 31, 2010 Debt Due 2015 [Member]	Dec. 31, 2011 Debt Due 2016 [Member]	Dec. 31, 2010 Debt Due 2016 [Member]	Dec. 31, 2011 Debt Due 2017 [Member]	Dec. 31, 2010 Debt Due 2017 [Member]	Dec. 31, 2011 Debt Due 2018 [Member]	Dec. 31, 2010 Debt Due 2018 [Member]	Dec. 31, 2011 Debt Due 2019 [Member]	Dec. 31, 2010 Debt Due 2019 [Member]	Dec. 31, 2011 Debt Due 2037 [Member]	Dec. 31, 2010 Debt Due 2037 [Member]	Dec. 31, 2011 Debt Due 2018 Number 2 [Member]	Dec. 31, 2010 Debt Due 2018 Number 2 [Member]	Dec. 31, 2008 Debt Due March 2018 [Member]	Dec. 31, 2010 Commercial Paper [Member]	Dec. 31, 2010 Term Loan Due 2012 [Member]	Dec. 31, 2011 Term Loan Due 2012 [Member]	Dec. 31, 2011 Interest Rate Swap 400M [Member]	Dec. 31, 2010 Interest Rate Swap 400M [Member]	Dec. 31, 2011 Interest Rate Swap 450M [Member]
Debt Instrument [Line Items]
Interest Rate				4.625%		3.875%		4.875%		5.00%		4.75%		5.75%		4.75%		6.25%		5.25%		5.60%
Commercial Paper																									$ 50,000,000
Other Debt	58,909,000	64,248,000
Total Debt	4,233,909,000	4,289,248,000
Notes payable & current portion of long-term obligations	550,000,000	50,000,000
Total Long-Term Debt	3,683,909,000	4,239,248,000		400,000,000	400,000,000	375,000,000	375,000,000	450,000,000	450,000,000	400,000,000	400,000,000	500,000,000	500,000,000	500,000,000	500,000,000	350,000,000	350,000,000	300,000,000	300,000,000	500,000,000	500,000,000	250,000,000	250,000,000			150,000,000	150,000,000
Notional Value																												400,000,000		450,000,000
Effective interest rate		3.70%	6.90%																					3.20%		0.32%
Weighted Average Spread over LIBOR																										Three month LIBOR
Debt Instrument, Basis Spread on Variable Rate																										0.42%
Payments or receipts in connection with unwinding swaps	0	(31,774,000)	20,281,000																					44,000,000
Derivative, Description of Variable Rate Basis																												One month LIBOR		Three month LIBOR
Derivative, Basis Spread on Variable Rate																												2.49%		3.05%
Derivative, Average Variable Interest Rate																											2.80%		2.80%	3.50%
Line of Credit Facility, Remaining Borrowing Capacity	1,250,000,000
Line of Credit Facility, Commitment Fee Amount	1,000,000	2,000,000	1,000,000
Long Term Debt By Maturity [Abstract]
Long-term Debt, Maturities, Repayments of Principal in Next Twelve Months	550,000,000
Long-term Debt, Maturities, Repayments of Principal in Year Two	375,000,000
Long-term Debt, Maturities, Repayments of Principal in Year Three	450,000,000
Long-term Debt, Maturities, Repayments of Principal in Year Four	400,000,000
Long-term Debt, Maturities, Repayments of Principal in Year Five	500,000,000
Long-term Debt, Maturities, Repayments of Principal after Year Five	$ 1,900,000,000