Acquisitions - Pro forma Information (Detail) (USD $) In Thousands, unless otherwise specified	7 Months Ended	12 Months Ended
Dec. 31, 2011	Dec. 31, 2011	Dec. 31, 2010
Business Acquisition [Line Items]
Total revenues actual since acquisition	$ 380,945
Total revenues pro forma		4,202,109	4,064,729
Net income actual since acquisition	18,586
Net income pro forma		$ 808,696	$ 295,486

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The pro forma net Income or Loss for the period as if the business combination or combinations had been completed at the beginning of a period.

+ References

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- Definition

The pro forma revenue for a period as if the business combination or combinations had been completed at the beginning of the period.

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- Definition

This element represents the amount of earnings or loss of the acquiree since the acquisition date included in the consolidated income statement for the reporting period.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 805

-SubTopic 10

-Section 50

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-Subparagraph (h)(1)

-URI http://asc.fasb.org/extlink&oid=7659399&loc=d3e1392-128463

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 141R

-Paragraph 68

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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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.

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This element represents the amount of revenue of the acquiree since the acquisition date included in the consolidated income statement for the reporting period.

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