Fair Value of Financial Instruments (Tables)

12 Months Ended

Dec. 31, 2013

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:

	December 31, 2013
	Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
	(in thousands)
Cash and cash equivalents:
Cash	$	27,488	$	—	$	—		$	27,488
Money market funds	183		—		—			183
Commercial paper	14,697		1		—			14,698
Total	42,368		1		—			42,369
Short-term investments:
Commercial paper	32,784		6		—			32,790
Corporate bonds	16,894		11		—			16,905
Municipal bonds	1,128		—		—			1,128
U.S. government agencies	4,004		—		—			4,004
Total	54,810		17		—			54,827
Long-term investments:
Asset-backed securities	5,497		4		—			5,501
U.S. government agencies	14,835		1		(3		)	14,833
Corporate bonds	15,256		22		(4		)	15,274
Total	35,588		27		(7		)	35,608
Total	132,766		45		(7		)	132,804

	December 31, 2012
	Amortized Cost		Unrealized Gains		Unrealized Losses		Fair Value
	(in thousands)
Cash and cash equivalents:
Cash	$	23,419	$	—	$	—	$	23,419
Money market funds	170		—		—		170
Commercial paper	11,294		2		—		11,296
Total	34,883		2		—		34,885
Short-term investments:
Commercial paper	21,078		2		—		21,080
U.S. government agencies	62,463		4		—		62,467
Total	83,541		6		—		83,547
Total	$	118,424	$	8	$	—	$	118,432

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:

	December 31, 2013
	Level 1		Level 2		Level 3		Fair Value
	(in thousands)
Commercial paper	$	—	$	47,488	$	—	$	47,488
U.S. government agencies	—		18,837		—		18,837
Municipal bonds	—		1,128		—		1,128
Corporate bonds	—		32,179		—		32,179
Asset-backed securities	—		5,501		—		5,501
Total	$	—	$	105,133	$	—	$	105,133

	December 31, 2012
	Level 1		Level 2		Level 3		Fair Value
	(in thousands)
Commercial paper	$	—	$	32,376	$	—	$	32,376
U.S. government agencies	—		62,467		—		62,467
Total	$	—	$	94,843	$	—	$	94,843

Schedule of Investments Classified by Contractual Maturity

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

	December 31, 2013
	Mature within One Year		After One Year through Two Years		Over Two Years		Fair Value
	(in thousands)
Commercial paper	$	47,488	$	—	$	—	$	47,488
U.S. government agencies	4,004		14,833		—		18,837
Municipal bonds	1,128		—		—		1,128
Corporate bonds	16,905		15,274		—		32,179
Asset-backed securities	—		—		5,501		5,501
Total	$	69,525	$	30,107	$	5,501	$	105,133

	December 31, 2012
	Mature within One Year		After One Year through Two Years		Over Two Years		Fair Value
	(in thousands)
Commercial paper	$	32,376	$	—	$	—	$	32,376
U.S. government agencies	62,467		—		—		62,467
Total	$	94,843	$	—	$	—	$	94,843