Fair Value of Financial Instruments (Tables)

9 Months Ended

Sep. 30, 2015

Fair Value Disclosures [Abstract]

Schedule of Cash and Cash Equivalents, Available-for-sale Securities Reconciliation

The Company's cash and cash equivalents, short-term investments, and long-term investments consist of the following:

	September 30, 2015
	Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
	(in thousands)
Cash and cash equivalents:
Cash	$	48,907	$	—	$	—		$	48,907
Money market funds	3,612		—		—			3,612
U.S. government agencies	2,400		—		—			2,400
Commercial paper	39,841		3		—			39,844
Total	94,760		3		—			94,763
Short-term investments:
Commercial paper	24,579		9		—			24,588
Corporate bonds	12,561		2		(3		)	12,560
Asset-backed securities	537		—		—			537
U.S. government agencies	41,675		22		—			41,697
Total	79,352		33		(3		)	79,382
Long-term investments:
Asset-backed securities	6,405		—		(1		)	6,404
U.S. government agencies	12,461		9		(2		)	12,468
Corporate bonds	6,862		1		(3		)	6,860
Total	25,728		10		(6		)	25,732
Total	$	199,840	$	46	$	(9	)	$	199,877

	December 31, 2014
	Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
	(in thousands)
Cash and cash equivalents:
Cash	$	36,024	$	—	$	—		$	36,024
Money market funds	39,180		—		—			39,180
U.S. government agencies	300		—		—			300
Commercial paper	1,000		—		—			1,000
Total	76,504		—		—			76,504
Short-term investments:
Commercial paper	4,998		1		—			4,999
Corporate bonds	12,438		6		(6		)	12,438
U.S. government agencies	33,280		3		(6		)	33,277
Total	50,716		10		(12		)	50,714
Long-term investments:
Asset-backed securities	16,092		5		(3		)	16,094
U.S. government agencies	20,243		22		(10		)	20,255
Corporate bonds	3,101		—		(2		)	3,099
Total	39,436		27		(15		)	39,448
Total	$	166,656	$	37	$	(27	)	$	166,666

Schedule of Assets Measured on Recurring Basis

The following table sets forth by level within the fair value hierarchy the fair value of the Company's available-for-sale securities measured on a recurring basis, excluding cash and money market funds:

	September 30, 2015
	Level 1		Level 2		Level 3		Fair Value
	(in thousands)
Commercial paper	$	—	$	64,432	$	—	$	64,432
U.S. government agencies	—		56,565		—		56,565
Corporate bonds	—		19,420		—		19,420
Asset-backed securities	—		6,941		—		6,941
Total	$	—	$	147,358	$	—	$	147,358

	December 31, 2014
	Level 1		Level 2		Level 3		Fair Value
	(in thousands)
Commercial paper	$	—	$	5,999	$	—	$	5,999
U.S. government agencies	—		53,832		—		53,832
Corporate bonds	—		15,537		—		15,537
Asset-backed securities	—		16,094		—		16,094
Total	$	—	$	91,462	$	—	$	91,462

Schedule of Available-for-Sale Securities by Contractual Maturity

The following summarizes the fair value of securities classified as available-for-sale by contractual maturity:

	September 30, 2015
	Mature within One Year		After One Year through Two Years		Over Two Years		Fair Value
	(in thousands)
Commercial paper	$	64,432	$	—	$	—	$	64,432
U.S. government agencies	44,097		12,468		—		56,565
Corporate bonds	12,560		6,860		—		19,420
Asset-backed securities	537		4,203		2,201		6,941
Total	$	121,626	$	23,531	$	2,201	$	147,358

	December 31, 2014
	Mature within One Year		After One Year through Two Years		Over Two Years		Fair Value
	(in thousands)
Commercial paper	$	5,999	$	—	$	—	$	5,999
U.S. government agencies	33,577		20,255		—		53,832
Corporate bonds	12,438		3,099		—		15,537
Asset-backed securities	—		7,327		8,767		16,094
Total	$	52,014	$	30,681	$	8,767	$	91,462