Acquisitions (Business Acquisition, Pro Forma Information) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Business Acquisition, Pro Forma Information [Abstract]
Revenues	$ 2,178,954	$ 1,960,851	$ 1,582,699
Operating income	79,159	65,152	54,947
Net income	$ 105,387	$ 68,841	$ 88,319
Business Acquisition, Pro Forma Income (Loss) from Continuing Operations before Changes in Accounting and Extraordinary Items, Net of Tax, Per Share, Basic	$ 1.50	$ 1.20	$ 1.03
Basic earnings per share (in dollars per share)	2.00	1.27	1.65
Business Acquisition, Pro Forma Income (Loss) from Continuing Operations before Changes in Accounting and Extraordinary Items, Net of Tax, Per Share, Diluted	1.48	1.18	1.01
Diluted earnings per share (in dollars per share)	$ 1.97	$ 1.25	$ 1.62
Weighted average number of shares outstanding	52,632	54,232	53,481
Weighted average number of shares and dilutive shares outstanding	53,411	55,124	54,555

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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