QUARTERLY SUPPLEMENTAL FINANCIAL DATA (UNAUDITED) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 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, 2015	Dec. 31, 2014	Dec. 31, 2013
Quarterly Financial Information Disclosure [Abstract]
Revenue	$ 62,312	[1]	$ 39,419	$ 58,092	[1]	$ 31,223	$ 56,173	[2]	$ 32,892	$ 64,127	[2]	$ 37,839	$ 191,046	$ 191,031	$ 146,639
Net income (loss)	$ 18,088		$ 7,047	$ (11,771)	[3]	$ 1,314	$ 13,126		$ 4,284	$ 20,422		$ 4,022	$ 14,678	$ 41,854	$ 74,052
Net income loss per common share [Abstract]
Basic (in dollars per share)	$ 0.39		$ 0.15	$ (0.25)		$ 0.03	$ 0.29		$ 0.09	$ 0.44		$ 0.09	$ 0.31	$ 0.90	$ 1.61
Diluted (in dollars per share)	$ 0.39		$ 0.15	$ (0.25)		$ 0.03	$ 0.28		$ 0.09	$ 0.44		$ 0.09	$ 0.31	$ 0.90	$ 1.59
Inventory write-downs				$ 33,000									$ 33,000	$ 3,900	$ 0

[1] (1) The Company receives significant license revenue in the second and fourth quarters; see Note 2 for further details.

[2] (1) The Company receives significant license revenue in the second and fourth quarters; see Note 2 for further details.

[3] Includes a $33.0 million write down of inventory; see Note 4 for further details.