Marketable Securities (Tables)

6 Months Ended

Jun. 30, 2016

Investments, Debt and Equity Securities [Abstract]

Schedule of available-for-sale marketable securities and cash and cash equivalents

Available-for-sale marketable securities and cash and cash equivalents consist of the following (in thousands):

	June 30, 2016
	Amortized Cost Value		Gross  Unrealized  Gains		Gross  Unrealized  Losses			Fair Value
Cash and cash equivalents:
Cash	$	3,303	$	—	$	—		$	3,303
Money market funds	114,750		—		—			114,750
Domestic corporate commercial paper	2,501		—		—			2,501
Total	$	120,554	$	—	$	—		$	120,554
Marketable securities:
Domestic corporate debt securities	$	108,873	$	6	$	(19	)	$	108,860
Domestic corporate commercial paper	84,202		175		—			84,377
Asset-backed securities	87,039		26		—			87,065
Total	$	280,114	$	207	$	(19	)	$	280,302

	December 31, 2015
	Amortized Cost Value		Gross  Unrealized  Gains		Gross  Unrealized  Losses			Fair Value
Cash and cash equivalents:
Cash	$	2,934	$	—	$	—		$	2,934
Money market funds	83,257		—		—			83,257
Domestic corporate commercial paper	39,984		—		—			39,984
Government-sponsored enterprise debt securities	15,996		—		—			15,996
Domestic corporate debt securities	10,007		—		—			10,007
Asset-backed securities	7,500		—		—			7,500
Total	$	159,678	$	—	$	—		$	159,678
Marketable securities:
Domestic corporate debt securities	$	173,142	$	—	$	(107	)	$	173,035
Domestic corporate commercial paper	84,004		154		—			84,158
Asset-backed securities	56,510		1		(43		)	56,468
Total	$	313,656	$	155	$	(150	)	$	313,661