Segment Information (Details 1) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Reconciliation of total adjusted segment income to consolidated income from continuing operations before income taxes
Adjusted segment income	$ 247,475	$ 185,511	$ 111,772
Gain on debt repurchase		1,634	10,429
Income from continuing operations before income taxes	$ 247,475	$ 187,145	$ 122,201

Amount represents the difference between the fair value of the payments made and the carrying amount of the debt at the time of its extinguishment.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 470

-SubTopic 50

-Section 40

-Paragraph 4

-URI http://asc.fasb.org/extlink&oid=6850294&loc=d3e12355-112629

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

-Publisher AICPA

-Name Accounting Principles Board Opinion (APB)

-Number 26

-Paragraph 20, 21

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

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-Section 45

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 470

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