Fair Value of Financial Instruments (Tables)

12 Months Ended

Dec. 31, 2016

Fair Value Disclosures [Abstract]

Assets and liabilities measured at fair value

Assets and liabilities measured at fair value on a recurring basis included the following as of December 31, 2016 and 2015 (in thousands):

	December 31, 2016								December 31, 2015
	Fair Value		Level 1		Level 2		Level 3		Fair Value		Level 1		Level 2		Level 3
Cash equivalents	$	48,136	$	48,136	$	—	$	—	$	61,986	$	61,986	$	—	$	—
Corporate bonds	60,676		—		60,676		—		56,109		—		56,109		—
Agency bonds	28,930		—		28,930		—		85,461		—		85,461		—
U.S. treasury securities	157,686		—		157,686		—		57,908		—		57,908		—
Commercial paper	10,473		—		10,473		—		—		—		—		—
Strategic investments	—		—		—		—		150		—		—		150
	$	305,901	$	48,136	$	257,765	$	—	$	261,614	$	61,986	$	199,478	$	150

Reconciliation of investment in debt securities

The following table presents a reconciliation of the investment in debt securities measured at fair value using significant unobservable inputs (Level 3) as of December 31, 2016 (in thousands):

Balance as of December 31, 2015	$	150
Fair value adjustment	(150		)
Balance as of December 31, 2016	$	—