Investments (Tables)

9 Months Ended

Sep. 30, 2014

Summary of Short-Term Investments

The following tables summarize our short-term investments (in thousands):

	Maturity (in years)		Amortized cost		Unrealized					Estimated fair value
					Gains		Losses
As of September 30, 2014
Corporate debt securities		2 or less	$	68,270	$	9	$	(42	)	$	68,237
Certificates of deposit		2 or less		13,870		—		—			13,870
Commercial paper		1 or less		2,000		—		—			2,000
Total			$	84,140	$	9	$	(42	)	$	84,107

	Maturity (in years)		Amortized cost		Unrealized					Estimated fair value
					Gains		Losses
As of December 31, 2013
Corporate debt securities		2 or less	$	71,402	$	39	$	(25	)	$	71,416
Certificates of deposit		2 or less		11,710		—		—			11,710
Commercial paper		1 or less		6,069		2		—			6,071
Debt securities of U.S. government-sponsored agencies		1 or less		7,000		1		—			7,001
Total			$	96,181	$	42	$	(25	)	$	96,198