Debt and Other Financing Arrangements (Summary of Company's Senior Notes) (Details) (USD $) In Thousands, unless otherwise specified	6 Months Ended		12 Months Ended
	Jun. 30, 2011		Dec. 31, 2010
Senior notes	$ 3,332,263	[1]	$ 3,391,668	[1]
Debt Instrument, Fair Value	3,244,674		3,227,404
Unsecured Senior Notes 8.125% Due February 2011 [Member]
Senior notes			13,900	[2]
Debt interest rate	8.125%		8.125%
Debt maturity date	February 2011		February 2011
Unsecured Senior Notes 5.45% Due August 2012 [Member]
Senior notes	97,116	[3]	104,823	[3]
Debt interest rate	5.45%		5.45%
Debt maturity date	August 2012		August 2012
Unsecured Senior Notes 6.25% Due February 2013 [Member]
Senior notes	62,647	[3]	62,617	[3]
Debt interest rate	6.25%		6.25%
Debt maturity date	February 2013		February 2013
Unsecured Senior Notes 5.125% Due October 2013 [Member]
Senior notes	116,545	[3]	160,212	[3]
Debt interest rate	5.125%		5.125%
Debt maturity date	October 2013		October 2013
Unsecured Senior Notes 5.25% Due January 2014 [Member]
Senior notes	335,859	[3]	335,848	[3]
Debt interest rate	5.25%		5.25%
Debt maturity date	January 2014		January 2014
Unsecured Senior Notes 5.7% Due May 2014 [Member]
Senior notes	310,474	[3]	309,048	[3]
Debt interest rate	5.70%		5.70%
Debt maturity date	May 2014		May 2014
Unsecured Senior Notes 5.2% Due January 2015 [Member]
Senior notes	244,862	[3]	244,839	[3]
Debt interest rate	5.20%		5.20%
Debt maturity date	January 2015		January 2015
Unsecured Senior Notes 5.25% Due June 2015 [Member]
Senior notes	400,702	[3]	397,700	[3]
Debt interest rate	5.25%		5.25%
Debt maturity date	June 2015		June 2015
Unsecured Senior Notes 6.5% Due May 2016 [Member]
Senior notes	467,894	[3]	466,644	[3]
Debt interest rate	6.50%		6.50%
Debt maturity date	May 2016		May 2016
Unsecured Senior Notes 7.625% Due September 2017 [Member]
Senior notes	149,319	[2]	149,265	[2]
Debt interest rate	7.625%		7.625%
Debt maturity date	September 2017		September 2017
Unsecured Senior Notes 7.875% Due May 2032 [Member]
Senior notes	299,087	[3]	299,065	[3]
Debt interest rate	7.875%		7.875%
Debt maturity date	May 2032		May 2032
Unsecured Senior Notes 6.375% Due May 2033 [Member]
Senior notes	398,381	[3]	398,344	[3]
Debt interest rate	6.375%		6.375%
Debt maturity date	May 2033		May 2033
Unsecured Senior Notes 6% Due January 2035 [Member]
Senior notes	299,377	[3]	299,363	[3]
Debt interest rate	6.00%		6.00%
Debt maturity date	January 2035		January 2035
Unsecured Senior Notes 7.375% Due June 2046 [Member]
Senior notes	$ 150,000	[3]	$ 150,000	[3]
Debt interest rate	7.375%		7.375%
Debt maturity date	June 2046		June 2046

[1] The recorded carrying value reflects the impact of various discounts and premiums that are amortized to interest cost over the respective terms of the senior notes

[2] Not redeemable prior to maturity, guaranteed on a senior basis by certain wholly-owned subsidiaries

[3] Redeemable prior to maturity, guaranteed on a senior basis by certain wholly-owned subsidiaries