Investments (Tables)

3 Months Ended

Mar. 31, 2015

Investments, Debt and Equity Securities [Abstract]

Summary of Amortized Cost and Fair Value of Investments

The amortized cost and fair value of our investments, with gross unrealized gains and losses, were as follows:

	Amortized Cost Basis		Gross Unrealized Gains		Gross Unrealized Losses			Aggregate Fair Value
	(in thousands)
At March 31, 2015
Short-term investments:
Corporate debt	$	45,940	$	1	$	(136	)	$	45,805
U.S. government agency debt		15,000		1		(7	)		14,994
Certificates of deposit		9,555		—		—			9,555
Total short-term investments	$	70,495	$	2	$	(143	)	$	70,354
Long-term investments:
Certificates of deposit	$	1,225	$	—	$	—		$	1,225
Total long-term investments	$	1,225	$	—	$	—		$	1,225

	Amortized Cost Basis		Gross Unrealized Gains		Gross Unrealized Losses			Aggregate Fair Value
	(in thousands)
At December 31, 2014
Short-term investments:
Corporate debt	$	51,241	$	8	$	(244	)	$	51,005
U.S. government agency debt		15,000		—		(25	)		14,975
Certificates of deposit		9,555		—		—			9,555
Total short-term investments	$	75,796	$	8	$	(269	)	$	75,535
Long-term investments:
Certificates of deposit	$	1,225	$	—	$	—		$	1,225
Total long-term investments	$	1,225	$	—	$	—		$	1,225