SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Tables)

12 Months Ended

Dec. 31, 2015

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES

Schedule of available-for-sale securities

Available‑for‑sale securities at December 31, 2015 consist of the following:

	December 31, 2015
			Gains in Accumulated		Losses in Accumulated
			Other Comprehensive		Other Comprehensive		Estimated Fair
(In thousands)	Amortized Cost		Income		Income		Value
Corporate bonds	$	179,471	$	2	$	(262)	$	179,211
U.S. government agency securities		7,057		—		(18)		7,039
Asset backed securities		77,661		—		(166)		77,495
Certificates of deposit		1,999		—		—		1,999
Total available-for-sale securities	$	266,188	$	2	$	(446)	$	265,744

Available‑for‑sale securities at December 31, 2014 consist of the following:

	December 31, 2014
			Gains in Accumulated		Losses in Accumulated
			Other Comprehensive		Other Comprehensive		Estimated Fair
(In thousands)	Amortized Cost		Income		Income		Value
Corporate bonds	$	141,239	$	20	$	(135)	$	141,124
U.S. government agency securities		18,687		8		(7)		18,688
Asset backed securities		60,821		17		(18)		60,820
Commercial paper		3,993		—		—		3,993
Total available-for-sale securities	$	224,740	$	45	$	(160)	$	224,625

Schedule of amounts recognized in accumulated other comprehensive income (loss) (AOCI)

The amount recognized in accumulated other comprehensive income (loss) (“AOCI”) for the years ended December 31, 2015 and 2014 were as follows (in thousands):

					Accumulated
	Cumulative		Unrealized		Other
	Translation		Gain (Loss)		Comprehensive
	Adjustment		on Securities		Income (Loss)
Balance at January 1, 2013	$	—	$	78	$	78
Other comprehensive (loss) income before reclassifications		—		90		90
Amounts reclassified from accumulated other comprehensive loss		—		(43)		(43)
Net current period change in accumulated other comprehensive income (loss)		—		47		47
Balance at December 31, 2013	$	—	$	125	$	125
Other comprehensive (loss) income before reclassifications		—		(200)		(200)
Amounts reclassified from accumulated other comprehensive loss		—		(40)		(40)
Net current period change in accumulated other comprehensive income (loss)		—		(240)		(240)
Balance at December 31, 2014	$	—	$	(115)	$	(115)
Other comprehensive (loss) income before reclassifications		11		(361)		(350)
Amounts reclassified from accumulated other comprehensive loss		—		32		32
Net current period change in accumulated other comprehensive income (loss)		11		(329)		(318)
Balance at December 31, 2015	$	11	$	(444)	$	(433)

Schedule of amounts reclassified from accumulated other comprehensive income (loss)

Amounts reclassified from accumulated other comprehensive income (loss) for the years ended December 31, 2015, 2014 and 2013 were as follows (in thousands):

	Affected Line Item in the	Year Ended December 31,
Details about AOCI  Components	Statement of Operations	2015		2014		2013
Change in value of available-for-sale investments
Sales and maturities of available-for-sale investments	Investment income	$	32	$	(40)	$	(43)
Total reclassifications		$	32	$	(40)	$	(43)

Schedule of estimated useful lives of fixed assets

	Estimated
Asset Classification	Useful Life
Laboratory equipment	3 - 5 years
Computer equipment and computer software	3 years
Leasehold improvements	Lesser of the remaining lease term or useful life
Furniture and fixtures	3 years
Buildings	30 years

Schedule of potentially issuable common shares not included in the computation of diluted net loss per share because they would have an anti-dilutive effect

The following potentially issuable common shares were not included in the computation of diluted net loss per share because they would have an anti‑dilutive effect due to net losses for each period (amounts are in thousands):

	2015	2014	2013
Shares issuable upon exercise of stock options	4,937	4,934	6,063
Shares issuable upon exercise of outstanding warrants(1)	—	—	155
Shares issuable upon the release of restricted stock awards	3,445	1,541	1,151
Shares issuable upon the vesting of restricted stock awards related to licensing agreement	—	24	49
	8,382	6,499	7,418

(1) At December 31, 2013, represents warrants to purchase 80,000 shares of common stock issued under a license agreement and warrants to purchase 75,000 shares of common stock issued under a consulting agreement.

Schedule of inventory

Inventory consists of the following (amount in thousands):

	December 31,
	2015		2014
Raw materials	$	1,772	$	1,019
Semi-finished and finished goods		4,905		2,998
Total inventory	$	6,677	$	4,017

Schedule of fair value measurements along with the level within the fair value hierarchy in which the fair value measurements fall

The following table presents the Company’s fair value measurements as of December 31, 2015 along with the level within the fair value hierarchy in which the fair value measurements in their entirety fall. Amounts in the table are in thousands.

			Fair Value Measurement at December 31, 2015 Using:
			Quoted Prices		Significant
			in Active		Other		Significant
			Markets for		Observable		Unobservable
	Fair Value at		Identical Assets		Inputs		Inputs
Description	December 31, 2015		(Level 1)		(Level 2)		(Level 3)
Cash and cash equivalents
Cash and money market	$	37,435	$	37,435	$	—	$	—
Commercial paper		3,700		—		3,700		—
Available-for-Sale
Marketable securities
Corporate bonds		179,211		—		179,211		—
Asset backed securities		77,495		—		77,495		—
U.S. government agency securities		7,039		—		7,039		—
Certificates of deposit		1,999		—		1,999		—
Total	$	306,879	$	37,435	$	269,444	$	—

The following table presents the Company’s fair value measurements as of December 31, 2014 along with the level within the fair value hierarchy in which the fair value measurements in their entirety fall. Amounts in the table are in thousands.

			Fair Value Measurement at December 31, 2014 Using:
			Quoted Prices		Significant
			in Active		Other		Significant
			Markets for		Observable		Unobservable
	Fair Value at		Identical Assets		Inputs		Inputs
Description	December 31, 2014		(Level 1)		(Level 2)		(Level 3)
Cash and cash equivalents
Cash and money market	$	53,569	$	53,569	$	—	$	—
Corporate bonds		4,562		—		4,562		—
Available-for-Sale
Marketable securities
Corporate bonds		141,124		—		141,124		—
U.S. government agency securities		18,688		—		18,688		—
Asset backed securities		60,820		—		60,820		—
Commercial paper		3,993		—		3,993		—
Total	$	282,756	$	53,569	$	229,187	$	—

Schedule of gross unrealized losses and fair values of investments in an unrealized loss position

The following table summarizes the gross unrealized losses and fair values of investments in an unrealized loss position as of December 31, 2015, aggregated by investment category and length of time that individual securities have been in a continuous unrealized loss position:

		December 31, 2015
		Less than 12 months			12 months or greater				Total
(In thousands)		Fair Value		Gross Unrealized Loss		Fair Value		Gross Unrealized Loss		Fair Value		Gross Unrealized Loss
Marketable Securities
Corporate bonds	$	166,238	$	(262)	$	—	$	—	$	166,238	$	(262)
U.S. government agency securities		7,039		(18)		—		—		7,039		(18)
Asset backed securities		72,792		(164)		3,887		(2)		76,679		(166)
Total	$	246,069	$	(444)	$	3,887	$	(2)	$	249,956	$	(446)

The following table summarizes the gross unrealized losses and fair value of investments in an unrealized loss position as of December 31, 2014, aggregated by investment category and length of time that individual securities have been in a continuous unrealized loss position:

		December 31, 2014
		Less than 12 months			12 months or greater				Total
(In thousands)		Fair Value		Gross Unrealized Loss		Fair Value		Gross Unrealized Loss		Fair Value		Gross Unrealized Loss
Marketable Securities
Corporate bonds	$	113,960	$	(135)	$	—	$	—	$	113,960	$	(135)
Asset backed securities		33,073		(18)		—		—		33,073		(18)
U.S. government agency securities		5,641		(7)		—		—		5,641		(7)
Total	$	152,674	$	(160)	$	—	$	—	$	152,674	$	(160)

Schedule of contractual maturities of available-for-sale investments

The following table summarizes contractual underlying maturities of the Company’s available‑for‑sale investments at December 31, 2015 (in thousands):

		Due one year or less			Due after one year through four years
Description		Cost		Fair Value		Cost		Fair Value
Marketable Securities
U.S. government agency securities	$	2,500	$	2,494	$	4,557	$	4,545
Corporate bonds		115,647		115,555		63,824		63,656
Certificates of deposit		1,999		1,999		—		—
Asset backed securities		373		373		77,288		77,122
Total	$	120,519	$	120,421	$	145,669	$	145,323