Acquisitions (Business Acquisition, Pro Forma Information) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
Dec. 31, 2013	Dec. 31, 2012
Business Acquisition, Pro Forma Information [Abstract]
Revenues	$ 1,582,699	$ 1,363,225
Operating income	54,947	49,022
Net income	$ 88,319	$ 58,213
Business Acquisition, Pro Forma Income (Loss) from Continuing Operations before Changes in Accounting and Extraordinary Items, Net of Tax, Per Share, Basic	$ 1.03	$ 0.94
Basic earnings per share (in dollars per share)	$ 1.65	$ 1.12
Business Acquisition, Pro Forma Income (Loss) from Continuing Operations before Changes in Accounting and Extraordinary Items, Net of Tax, Per Share, Diluted	$ 1.01	$ 0.92
Diluted earnings per share (in dollars per share)	$ 1.62	$ 1.09
Weighted average number of shares outstanding	53,481	52,103
Weighted average number of shares and dilutive shares outstanding	54,555	53,190

The pro forma basic net income per share for a period as if the business combination or combinations had been completed at the beginning of a period.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 805

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (h)(2)-(3)

-URI http://asc.fasb.org/extlink&oid=56956515&loc=d3e1392-128463

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The pro forma diluted net income per share for a period as if the business combination or combinations had been completed at the beginning of a period.

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The pro forma income from continuing operations before changes in accounting and extraordinary items, net of tax effect per basic share of common stock for a period as if the business combination or combinations had been completed at the beginning of a period.

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The pro forma income from continuing operations before changes in accounting and extraordinary items, net of tax effect, for the period as if the business combination or combinations had been completed at the beginning of a period.

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