Selected Quarterly Financial Data - Unaudited (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenues	$ 340,378	$ 327,169	$ 360,460	$ 372,033	$ 370,124	$ 343,236	$ 331,514	$ 247,739	$ 1,400,040	$ 1,292,613	$ 379,372
Gross Profit	134,640	134,587	151,800	149,001	137,490	111,598	88,062	88,945	570,028	426,095	201,398
Net Income	$ (7,355)	$ 219	$ 31,054	$ 4,875	$ 49,705	$ 136	$ (37,060)	$ 55,863	$ 28,793	$ 68,644	$ 63,084
Basic	$ (0.36)	$ 0.01	$ 1.53	$ 0.24	$ 2.47	$ 0.01	$ (1.87)	$ 3.03	$ 1.41	$ 3.50	$ 3.90
Diluted	$ (0.36)	$ 0.01	$ 1.44	$ 0.23	$ 2.33	$ 0.01	$ (1.87)	$ 2.86	$ 1.33	$ 3.29	$ 3.66
Restructuring, strategic transaction and integration expenses	$ 41,100								$ 105,390	$ 77,967	$ 15,348
Contractsettlements	$ 8,600								$ 41,613	$ 0	$ 0