Fair Value of Financial Instruments (Tables)

3 Months Ended

Mar. 31, 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:

	March 31, 2015
	Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
	(in thousands)
Cash and cash equivalents:
Cash	$	33,097	$	—	$	—		$	33,097
Money market funds	41,722		—		—			41,722
Commercial paper	3,198		1		—			3,199
Total	78,017		1		—			78,018
Short-term investments:
Commercial paper	8,929		7		—			8,936
Corporate bonds	11,206		4		(1		)	11,209
Asset-backed securities	225		—		—			225
U.S. government agencies	44,547		16		(1		)	44,562
Total	64,907		27		(2		)	64,932
Long-term investments:
Asset-backed securities	13,874		4		(3		)	13,875
U.S. government agencies	13,907		9		—			13,916
Corporate bonds	3,101		—		(1		)	3,100
Total	30,882		13		(4		)	30,891
Total	$	173,806	$	41	$	(6	)	$	173,841

	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:

	March 31, 2015
	Level 1		Level 2		Level 3		Fair Value
	(in thousands)
Commercial paper	$	—	$	12,135	$	—	$	12,135
U.S. government agencies	—		58,478		—		58,478
Corporate bonds	—		14,309		—		14,309
Asset-backed securities	—		14,100		—		14,100
Total	$	—	$	99,022	$	—	$	99,022

	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:

	March 31, 2015
	Mature within One Year		After One Year through Two Years		Over Two Years		Fair Value
	(in thousands)
Commercial paper	$	12,135	$	—	$	—	$	12,135
U.S. government agencies	44,562		13,916		—		58,478
Corporate bonds	11,209		3,100		—		14,309
Asset-backed securities	225		7,611		6,264		14,100
Total	$	68,131	$	24,627	$	6,264	$	99,022

	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