SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Net Loss Per Common Share (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
Numerator:
Net income	$ 18,088	$ 7,047	$ (11,771)	[1]	$ 1,314	$ 13,126	$ 4,284	$ 20,422	$ 4,022	$ 14,678	$ 41,854	$ 74,052
Denominator:
Weighted average common shares outstanding - Basic (in shares)										46,816,394	46,252,960	45,898,019
Effect of dilutive shares:
Common stock equivalents arising from stock options and ESPP (in shares)										267,145	265,129	458,574
Restricted stock awards and units (in shares)										410,649	167,056	187,012
Weighted average common shares outstanding - Diluted (in shares)										47,494,188	46,685,145	46,543,605
Net income (loss) per common share:
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
Anti-dilutive shares excluded from the calculation of diluted net loss per common share (in shares)										17,055	87,894	140,839
Deferred revenue [Abstract]
License fee agreement, term of agreement (in years)										6 years 4 months 24 days
Taxes, Other										$ 1,300	$ 4,300	$ 178
Research and Development [Abstract]
Development and operations in the Company’s facilities										34,348	27,891	23,491
PPG OLED Materials Agreement (Note 8)										7,912	10,614	7,470
Costs incurred under sponsored research agreements										1,795	2,014	2,671
Scientific Advisory Board compensation										586	635	583
Research and Development Expense, Total										$ 44,641	$ 41,154	$ 34,215

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