Fair Value Measurements (Tables)

3 Months Ended

Mar. 31, 2016

Fair Value Disclosures [Abstract]

Schedule of Assets and Liabilities Measured at Fair Value on Recurring Basis

Assets and liabilities measured at fair value on a recurring basis are as follows (in thousands):

			Fair Value Measurements Using
			Quoted Pricesin Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
As of March 31, 2016:
Assets:
Current:
Cash equivalents	$	42,787	$	42,787	$	—	$	—
Short-term investments:
Commercial paper		1,998		—		1,998		—
United States Treasury securities		3,003		3,003		—		—
Corporate debt securities		26,948		—		26,948		—
Sub-total short-term investments		31,949		3,003		28,946		—
Long-term investments:
United States Treasury securities		5,003		5,003		—		—
Asset-backed securities		9,014		—		9,014		—
Corporate debt securities		11,540		—		11,540		—
Sub-total long-term investments		25,557		5,003		20,554		—
Total assets measured at fair value	$	100,293	$	50,793	$	49,500	$	—
As of December 31, 2015:
Assets:
Current:
Cash equivalents	$	46,545	$	46,545	$	—	$	—
Short-term investments:
Commercial paper		2,996		—		2,996		—
Corporate debt securities		39,514		—		39,514		—
Sub-total short-term investments		42,510		—		42,510		—
Long-term investments:
United States Treasury securities		1,999		1,999		—		—
Asset-backed securities		10,912		—		10,912		—
Corporate debt securities		16,903		—		16,903		—
Sub-total long-term investments		29,814		1,999		27,815		—
Total assets measured at fair value	$	118,869	$	48,544	$	70,325	$	—

Schedule of Available-for-sale Investments

As of March 31, 2016 and December 31, 2015 available-for-sale investments are detailed as follows (in thousands):

	March 31, 2016
	Gross Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Market Value
Short-term investments:
Commercial paper	$	1,998	$	—	$	—		$	1,998
United States Treasury securities	$	3,002	$	1		—		$	3,003
Corporate debt securities		26,964		5		(21	)		26,948
	$	31,964	$	6	$	(21	)	$	31,949
Long-term investments:
United States Treasury securities	$	4,999	$	4	$	—		$	5,003
Asset-backed securities		9,010		5		(1	)		9,014
Corporate debt securities		11,552		4		(16	)		11,540
	$	25,561	$	13	$	(17	)	$	25,557

	December 31, 2015
	Gross Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Market Value
Short-term investments:
Commercial paper	$	2,996	$	—	$	—		$	2,996
Corporate debt securities		39,575		—		(61	)		39,514
	$	42,571	$	—	$	(61	)	$	42,510
Long-term investments:
United States Treasury securities	$	2,006	$	—	$	(7	)	$	1,999
Asset-backed securities		10,928		—		(16	)		10,912
Corporate debt securities		16,990		—		(87	)		16,903
	$	29,924	$	—	$	(110	)	$	29,814

Schedule of Available-for-sale Investments in Unrealized Loss Position

Available-for-sale investments that are in an unrealized loss position as of March 31, 2016 are as follows (in thousands):

	EstimatedFair Value		Gross Unrealized Losses
Asset-backed securities	$	2,000	$	(1	)
Corporate debt securities		19,079		(37	)
	$	21,079	$	(38	)