Selected Quarterly Financial Data (Unaudited) (Details) - Selected Quarterly Financial Data (Unaudited) - 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]
Revenues	$ 283,667	$ 284,095	$ 280,734	$ 268,347	$ 279,977	$ 256,801	$ 220,920	$ 227,378	$ 1,116,843	$ 985,076	$ 555,048
Gross Profit	169,254	170,227	171,773	163,017	174,430	163,012	128,407	130,163	674,271	596,012	261,360
Operating Income	60,796	86,828	92,368	87,579	64,475	90,767	66,102	73,267	327,571	294,611	60,816
Net Income (Loss), Amount	$ 32,455	$ 47,909	$ 61,993	$ 41,886	$ 32,785	$ 47,967	$ 32,508	$ 37,538	$ 184,243	$ 150,798	$ 13,884
Net Income (Loss), Per Basic Share (in Dollars per share)	$ 0.26	$ 0.38	$ 0.51	$ 0.35	$ 0.27	$ 0.40	$ 0.28	$ 0.33	$ 1.50	$ 1.29	$ 0.13
Net Income (Loss), Per Diluted Share (in Dollars per share)	$ 0.26	$ 0.38	$ 0.50	$ 0.34	$ 0.27	$ 0.39	$ 0.27	$ 0.31	$ 1.47	$ 1.22	$ 0.13