Selected Quarterly Financial Data (Unaudited) - Selected Quarterly Financial Data (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended												6 Months Ended			9 Months Ended			12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2013	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Revenues	$ 279,977	$ 256,801	$ 220,920	$ 227,378	$ 202,856	$ 127,698	$ 133,872	$ 90,622	$ 84,953	$ 81,892	$ 77,012	$ 73,854	$ 448,298	$ 224,494	$ 150,866	$ 705,099	$ 352,192	$ 232,758	$ 985,076	$ 555,048	$ 317,711
Gross Profit	174,430	163,012	128,407	130,163	105,333	45,500	60,871	49,656	46,970	43,697	42,092	39,145	258,570	110,527	81,237	421,582	156,027	124,934	596,012	261,360	171,904
Operating Income (Loss)	64,475	90,767	66,102	73,267	48,670	(12,030)	736	23,440	25,176	22,188	22,251	18,589	139,369	24,176	40,840	230,136	12,146	63,028	294,611	60,816	88,204
Net Income (loss) From Continuing Operations, Amount	$ 32,785	$ 47,967	$ 32,508	$ 37,538	$ 17,979	$ (12,333)	$ (752)	$ 9,494	$ 16,678	$ 12,205	$ 12,637	$ 10,842	$ 70,046	$ 8,742	$ 23,479	$ 118,013	$ (3,591)	$ 35,684	$ 150,798	$ 14,388	$ 52,362
Income (loss) from continuing operations, basic (in Dollars per share)	$ 0.27	$ 0.40	$ 0.28	$ 0.33	$ 0.17	$ (0.12)	$ (0.01)	$ 0.10	$ 0.17	$ 0.13	$ 0.13	$ 0.11	$ 0.61	$ 0.09	$ 0.24	$ 1.02	$ (0.04)	$ 0.37	$ 1.29	$ 0.14	$ 0.54
Income (loss) from continuing operations, diluted (in Dollars per share)	$ 0.27	$ 0.39	$ 0.27	$ 0.31	$ 0.16	$ (0.12)	$ (0.01)	$ 0.08	$ 0.13	$ 0.11	$ 0.11	$ 0.10	$ 0.57	$ 0.07	$ 0.21	$ 0.96	$ (0.04)	$ 0.32	$ 1.22	$ 0.13	$ 0.46
Net Income (Loss), Amount	$ 32,785	$ 47,967	$ 32,508	$ 37,538	$ 17,979	$ (12,333)	$ (1,256)	$ 9,494	$ 16,678	$ 12,205	$ 12,637	$ 10,842	$ 70,046	$ 8,238	$ 23,479	$ 118,013	$ (4,095)	$ 35,684	$ 150,798	$ 13,884	$ 52,362
Earnings Per Share, Basic	$ 0.27	$ 0.40	$ 0.28	$ 0.33	$ 0.17	$ (0.12)	$ (0.01)	$ 0.10	$ 0.17	$ 0.13	$ 0.13	$ 0.11	$ 0.61	$ 0.08	$ 0.24	$ 1.02	$ (0.04)	$ 0.37	$ 1.29	$ 0.13	$ 0.54
Earnings Per Share, Diluted	$ 0.27	$ 0.39	$ 0.27	$ 0.31	$ 0.16	$ (0.12)	$ (0.01)	$ 0.08	$ 0.13	$ 0.11	$ 0.11	$ 0.10	$ 0.57	$ 0.07	$ 0.21	$ 0.96	$ (0.04)	$ 0.32	$ 1.22	$ 0.13	$ 0.46
Pipeline Reserve Error [Member]
Revenues					$ (1,000)	$ (8,100)	$ (1,400)										$ (9,500)			$ (10,500)
Estimates And Cut - Off Errors [Member]
Revenues					$ (16,500)	$ (2,900)	$ (1,700)										$ (4,600)			$ (21,000)