Business Acquisitions (Future Amortization Expense) (Details) (USD $)	12 Months Ended
Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Acquired Intangible Assets, Amortization Expense, Fiscal Year Maturity [Abstract]
For the year ended December 31, 2013	$ 7,067,000
For the year ended December 31, 2014	6,688,000
For the year ended December 31, 2015	6,024,000
For the year ended December 31, 2016	5,705,000
For the year ended December 31, 2017	5,226,000
Thereafter	21,881,000
Estimated future amortization expense	52,591,000	38,386,000
Amortization expense, acquired intangible assets	$ 6,100,000	$ 4,800,000	$ 3,700,000

The aggregate expense charged against earnings to allocate the cost of intangible assets (nonphysical assets not used in production) in a systematic and rational manner to the periods expected to benefit from such assets. As a noncash expense, this element is added back to net income when calculating cash provided by or used in operations using the indirect method.

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-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 142

-Paragraph 45

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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

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

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-Name Accounting Standards Codification

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