QUARTERLY RESULTS OF OPERATIONS - UNAUDITED (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016
Quarterly Financial Information Disclosure [Abstract]
Revenue	$ 235,224	$ 268,944	$ 256,863	$ 225,756	$ 318,920	$ 302,192	$ 272,048	$ 268,952	$ 986,787	$ 1,162,112	$ 955,419
Gross profit	168,633	204,435	182,620	159,194	226,003	220,514	187,538	181,918	714,882	815,973	626,970
Net income (loss)	$ 16,817	$ 89,685	$ (2,468)	$ (24,222)	$ 22,310	$ 21,245	$ (1,266)	$ (8,998)	$ 79,812	$ 33,291	$ (28,369)
Diluted net income (loss) per share (in dollars per share)	$ 0.20	$ 1.02	$ (0.03)	$ (0.27)	$ 0.24	$ 0.23	$ (0.01)	$ (0.10)	$ 0.90	$ 0.36	$ (0.35)