QUARTERLY SUPPLEMENTAL FINANCIAL DATA (UNAUDITED) (Details) (USD $)	3 Months Ended												12 Months Ended
	Dec. 31, 2014		Sep. 30, 2014	Jun. 30, 2014		Mar. 31, 2014	Dec. 31, 2013		Sep. 30, 2013	Jun. 30, 2013		Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Quarterly Financial Information Disclosure [Abstract]
Revenue	$ 56,173,000	[1]	$ 32,892,000	$ 64,127,000	[1]	$ 37,839,000	$ 49,478,000	[1],[2]	$ 32,826,000	$ 49,359,000	[1]	$ 14,976,000	$ 191,031,000	$ 146,639,000	$ 83,244,000
Net income	13,126,000		4,284,000	20,422,000		4,022,000	57,886,000	[3]	5,542,000	15,382,000		(4,758,000)	41,854,000	74,052,000	9,660,000
Net income loss per common share [Abstract]
Basic (in dollars per share)	$ 0.29		$ 0.09	$ 0.44		$ 0.09	$ 1.26		$ 0.12	$ 0.34		$ (0.10)	$ 0.90	$ 1.61	$ 0.21
Diluted (in dollars per share)	$ 0.28		$ 0.09	$ 0.44		$ 0.09	$ 1.24		$ 0.12	$ 0.33		$ (0.10)	$ 0.90	$ 1.59	$ 0.21
Revenue recognized relating to cash payments received							1,500,000
Valuation allowances released													$ 59,400,000

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

[2] Includes $1.5 million of revenue that was recognized relating to cash payments received in a prior year that were creditable against license fees and/or royalties for which the Company determined there was no appreciable likelihood of executing a commercial license agreement with the customer (see Note 2).

[3] During the three months ended December 31, 2013, the Company released income tax valuation allowances of $59.4 million.