Debt - LT Debt (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended			12 Months Ended											12 Months Ended					3 Months Ended		12 Months Ended				12 Months Ended		12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Jul. 03, 2010	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Oct. 01, 2011	Dec. 31, 2011 Interest Rate Swap [Member]	Dec. 31, 2010 Interest Rate Swap [Member]	Dec. 31, 2011 Revolving Credit Facility due in 2016 [Member]	Jul. 31, 2011 Revolving Credit Facility due in 2016 [Member]	Dec. 31, 2010 Revolving Credit Facility due in 2016 [Member]	Dec. 31, 2011 Asset Securitization Program [Member]	Dec. 31, 2010 Asset Securitization Program [Member]	Dec. 31, 2010 Senior Notes Due in 2010 [Member]	Dec. 31, 2009 Senior Notes Due in 2010 [Member]	Dec. 31, 2011 Senior Notes Due in 2010 [Member]	Dec. 31, 2011 Bank Term Loan Due in 2012 [Member]	Dec. 31, 2010 Bank Term Loan Due in 2012 [Member]	Dec. 31, 2011 Senior Notes Due in 2013 [Member]	Dec. 31, 2010 Senior Notes Due in 2013 [Member]	Dec. 31, 2011 Notes Due in 2015 [Member]	Dec. 31, 2010 Notes Due in 2015 [Member]	Dec. 31, 2011 Senior Debentures Due in 2018 [Member]	Dec. 31, 2010 Senior Debentures Due in 2018 [Member]	Dec. 31, 2011 Notes Due in 2021 [Member]	Dec. 31, 2010 Notes Due in 2021 [Member]	Dec. 31, 2009 Notes Due in 2020 [Member]	Dec. 31, 2011 Notes Due in 2020 [Member]	Dec. 31, 2010 Notes Due in 2020 [Member]	Dec. 31, 2011 Senior Debentures Due in 2027 [Member]	Dec. 31, 2010 Senior Debentures Due in 2027 [Member]	Dec. 31, 2011 Other LT Obligations [Member]	Dec. 31, 2010 Other LT Obligations [Member]
Debt Instrument [Line Items]
Repurchase/repayment of senior notes				$ (19,324)	$ (69,545)	$ (135,658)									$ (69,545)	$ (130,455)				$ (17,893)
Long-term Debt, Maturities, Repayments of Principal in Next Twelve Months	33,843			33,843
Long-term Debt, Maturities, Repayments of Principal in Year Two	343,292			343,292
Long-term Debt, Maturities, Repayments of Principal in Year Three	304,221			304,221
Long-term Debt, Maturities, Repayments of Principal in Year Four	260,519			260,519
Long-term Debt, Maturities, Repayments of Principal in Year Five	74,035			74,035
Long-term Debt, Maturities, Repayments of Principal after Year Five	945,756			945,756
Line of Credit Facility, Maximum Borrowing Capacity										1,200,000	800,000
Line of Credit Facility, Amount Outstanding	74,000			74,000						74,000		0
Asset Securitization Program Maximum Capacity	775,000			775,000			600,000
Debt Instruments [Abstract]
Long-term Line of Credit, Noncurrent	200,000			200,000														0	200,000
Senior Notes, Noncurrent																				341,937	349,833
Unsecured Long-term Debt, Noncurrent																								198,660	198,450						197,890	197,750
Long Term Notes																						260,461	249,155			249,278	249,199		299,927	299,918
Derivative Liabilities, Noncurrent								0	14,082
Other Long-term Debt, Noncurrent																																	25,670	2,816
Long-term debt	1,927,823	1,761,203		1,927,823	1,761,203
Debt Instrument, Interest Rate, Stated Percentage	2.63%			2.63%													9.15%			6.875%		3.375%		6.875%		5.125%			6.00%		7.50%
Net proceeds from note offering				0	494,325	297,430
Debt Instrument, Fair Value																				352,000	385,000	250,000	243,000	216,000	218,000	247,500	238,000		315,000	306,000	244,000	204,000
Repayments of Other Long-term Debt		9,000
Loss on prepayment of debt				895	1,570	5,312
Loss on prepayment of debt, net of tax	(549)		(964)		964	3,228
Extinguishment of Debt Gain Loss Net of Tax Per Share Basic and Diluted			$ 0.01		$ (0.01)	$ 0.03
Proceeds from Issuance of Long-term Debt																						250,000				250,000		300,000
Investment Income, Interest				6,113	5,052	2,964
Interest Paid				104,340	80,686	79,952
Asset Securitization Program Amount Outstanding													280,000	0
Accounts receivable, net	$ 4,482,117	$ 4,102,870		$ 4,482,117	$ 4,102,870								$ 1,562,613
Asset Securitization Program Interest Rate Spread At End of Period													0.40%
Asset Securitization Program Facility Fee													0.40%