SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Tables)

12 Months Ended

Dec. 31, 2014

Accounting Policies [Abstract]

Short-term investments

Investments at December 31, 2014 and 2013 consist of the following (in thousands):

	Amortized		Unrealized					Aggregate Fair
Investment Classification	Cost		Gains		(Losses)			Market Value
December 31, 2014
Certificates of deposit	$	11,373	$	4	$	(13	)	$	11,364
Corporate bonds	228,799		14		(41		)	228,772
U.S. Government bonds	5,999		—		—			5,999
	$	246,171	$	18	$	(54	)	$	246,135
December 31, 2013
Certificates of deposit	$	11,358	$	2	$	(16	)	$	11,344
Corporate bonds	190,738		33		(48		)	190,723
U.S. Government bonds	3,074		—		—			3,074
Convertible notes	4,300		—		—			4,300
	$	209,470	$	35	$	(64	)	$	209,441

Assets and liabilities carried at fair value measured on a recurring basis

The following table provides the assets and liabilities carried at fair value measured on a recurring basis as of December 31, 2014 (in thousands):

			Fair Value Measurements, Using
	Total carrying value as of December 31, 2014		Quoted prices in active markets (Level 1)		Significant other observable inputs (Level 2)		Significant unobservable inputs (Level 3)
Cash equivalents	$	970	$	970	$	—	$	—
Short-term investments	243,088		243,088		—		—
Long-term investments	3,047		3,047		—		—

The following table provides the assets and liabilities carried at fair value measured on a recurring basis as of December 31, 2013 (in thousands):

			Fair Value Measurements, Using
	Total carrying value as of December 31, 2013		Quoted prices in active markets  (Level 1)		Significant other observable inputs (Level 2)		Significant unobservable inputs (Level 3)
Cash equivalents	$	7,600	$	7,600	$	—	$	—
Short-term investments	202,024		202,024		—		—
Long-term investments	7,417		3,117		—		4,300

Reconciliation of the changes in fair value of the Company's investments in convertible notes

The following table is a reconciliation of the changes in fair value of the Company’s investments in convertible notes for the years ended December 31, 2014 and 2013, which had been classified in Level 3 in the fair value hierarchy (in thousands):

	Year Ended December 31,
	2014			2013
Fair value of notes, beginning of year	$	4,300		$	4,300
Repayments of notes	(4,300		)	—
Fair value of notes, end of year	$	—		$	4,300

Basic and diluted net income (loss) per common share

The following table is a reconciliation of net income and the shares used in calculating basic and diluted net income per common share for the years ended December 31, 2014, 2013 and 2012 (in thousands, except share and per share data):

	Year Ended December 31,
	2014		2013		2012
Numerator:
Net income	$	41,854	$	74,052	$	9,660
Denominator:
Weighted average common shares outstanding – Basic	46,252,960		45,898,019		45,951,276
Effect of dilutive shares:
Common stock equivalents arising from stock options and ESPP	265,129		458,574		648,661
Restricted stock awards and units and performance units	167,056		187,012		283,665
Weighted average common shares outstanding – Diluted	46,685,145		46,543,605		46,883,602
Net income per common share:
Basic	$	0.90	$	1.61	$	0.21
Diluted	$	0.90	$	1.59	$	0.21

Research and development expenses

Research and development expenses consist of the following (in thousands):

	Year Ended December 31,
	2014		2013		2012
Development and operations in the Company’s facilities	$	27,891	$	23,491	$	21,381
PPG OLED Materials Agreement (Note 8)	10,614		7,470		6,170
Costs incurred under sponsored research agreements	2,014		2,671		2,058
Scientific Advisory Board compensation	635		583		423
	$	41,154	$	34,215	$	30,032

Non-cash activities

The following non-cash activities occurred (in thousands):

	Year Ended December 31,
	2014			2013			2012
Unrealized (loss) gain on available-for-sale securities	$	(7	)	$	(10	)	$	(31	)
Common stock issued to Board of Directors and Scientific Advisory Board that was earned in a previous period	323			315			328
Common stock issued to employees that was accrued for in a previous period	749			282			252
Property and equipment purchases included in accounts payable	965			420			165