Debt Level 4 (Details) (USD $) In Thousands	Sep. 30, 2011	Dec. 31, 2010
Debt Instrument [Line Items]
Bank credit facility due March 2016	$ 65,000	$ 0
Total debt	1,887,584	1,854,882
Less current maturities	(23,685)	(22,502)
Total long-term debt	1,863,899	1,832,380
Unsecured Debt [Member]
Debt Instrument [Line Items]
Unamortized pricing discounts and other	(5,030)	(6,106)
Unsecured Debt [Member] \| February 2013 [Member]
Debt Instrument [Line Items]
Senior Notes	4,857	8,557
Unsecured Debt [Member] \| October 2014 [Member]
Debt Instrument [Line Items]
Senior Notes	180,692	180,692
Unsecured Debt [Member] \| April 2015 [Member]
Debt Instrument [Line Items]
Senior Notes	136,465	157,250
Unsecured Debt [Member] \| April 2016 [Member]
Debt Instrument [Line Items]
Senior Notes	197,377	212,927
Unsecured Debt [Member] \| June 2017 [Member]
Debt Instrument [Line Items]
Senior Notes	295,000	295,000
Unsecured Debt [Member] \| October 2018 [Member]
Debt Instrument [Line Items]
Senior Notes	250,000	250,000
Unsecured Debt [Member] \| May 2019 [Member]
Debt Instrument [Line Items]
Senior Notes	250,000	250,000
Unsecured Debt [Member] \| November 2021 [Member]
Debt Instrument [Line Items]
Senior Notes	150,000	150,000
Unsecured Debt [Member] \| April 2027 [Member]
Debt Instrument [Line Items]
Senior Notes	200,000	200,000
Capital Lease Obligations [Member]
Debt Instrument [Line Items]
Obligations under capital leases	126,658	118,339
Mortgages [Member]
Debt Instrument [Line Items]
Mortgage notes and other debt, maturities through 2047	$ 36,565	$ 38,223

The amount of debt discount (net of debt premium) that was originally recognized at the issuance of the instrument that has yet to be amortized.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 835

-SubTopic 30

-Section 45

-Paragraph 4

-URI http://asc.fasb.org/extlink&oid=6451184&loc=d3e28567-108399

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 835

-SubTopic 30

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-URI http://asc.fasb.org/extlink&oid=6451184&loc=d3e28555-108399

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher AICPA

-Name Accounting Principles Board Opinion (APB)

-Number 21

-Paragraph 16

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 835

-SubTopic 30

-Section 55

-Paragraph 8

-URI http://asc.fasb.org/extlink&oid=6584090&loc=d3e28878-108400

Reference 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 835

-SubTopic 30

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-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6451184&loc=d3e28551-108399

Reference 6: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

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-URI http://asc.fasb.org/extlink&oid=6451184&loc=d3e28541-108399

Reference 7: http://www.xbrl.org/2003/role/presentationRef

-Publisher AICPA

-Name Accounting Principles Board Opinion (APB)

-Number 21

-Paragraph 20

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details