Quarterly Financial Data (Unaudited) - Schedule of Quarterly Financial Information (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Quarterly Financial Information Disclosure [Abstract]
Revenue	$ 270,418	$ 279,993	$ 269,220	$ 271,073	$ 270,311	$ 264,720	$ 252,227	$ 242,095	$ 1,090,704	$ 1,029,353	$ 1,000,133
Gross profit	68,727	67,781	65,094	61,946	62,539	63,611	58,980	55,065	263,548	240,194	229,459
Net income (loss)	$ 5,047	$ 4,341	$ (2,324)	$ (2,693)	$ (40,929)	$ 3,936	$ 3,655	$ 275	$ 4,370	$ (33,063)	$ 43,736
Net income (loss) per share:
Earnings Per Share, Basic	$ 0.09	$ 0.08	$ (0.04)	$ (0.05)	$ (0.77)	$ 0.07	$ 0.07	$ 0.01	$ 0.08	$ (0.63)	$ 0.84
Diluted (in USD per share)	$ 0.09	$ 0.08	$ (0.04)	$ (0.05)	$ (0.77)	$ 0.07	$ 0.07	$ 0.01	$ 0.08	$ (0.63)	$ 0.82
Effect of Fourth Quarter Events [Line Items]
Goodwill impairment charge					$ (37,539)				$ 0
Decrease in contingent consideration liability									$ (10,417)	$ 270	$ 37,873