Acquisitions and Dispositions (Details) (USD $)	3 Months Ended
Mar. 31, 2011	Mar. 31, 2012	Dec. 31, 2011
Acquisitions and Dispositions
Reduction of contingent consideration liabilities	$ 3,966,000
Assets held-for-sale, current		$ 3,300,000	$ 7,200,000

This element represents the amount of any change, including any differences arising upon settlement, recognized during the reporting period in the value of a liability, arising from an item of contingent consideration, assumed in a business combination.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 805

-SubTopic 30

-Section 50

-Paragraph 4

-Subparagraph (a)(1)

-URI http://asc.fasb.org/extlink&oid=6911361&loc=d3e7008-128479

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 141R

-Paragraph 72

-Subparagraph b

-Clause 1

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration