Acquisitions - Summary of Pro Forma Results of Operations (Detail) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Business Combinations [Abstract]
Revenue	$ 2,296,630	$ 2,309,491	$ 2,303,678
Income from continuing operations	$ 189,563	$ 188,977	$ 124,982
Income per common share from continuing operations—basic	$ 2.28	$ 2.27	$ 1.49
Income per common share from continuing operations—diluted	$ 2.24	$ 2.21	$ 1.46

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=65885119&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 net Income or Loss for the period as if the business combination or combinations had been completed at the beginning of a period.

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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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