Investments (Tables)

12 Months Ended

Dec. 31, 2015

Investments, Debt and Equity Securities [Abstract]

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 December 31, 2015
Corporate debt securities	2 or less	$	81,054	$	16	$	(103	)	$	80,967
Certificates of deposit	2 or less	13,640		—		—			13,640
Commercial paper	1 or less	3,490		6		—			3,496
Total		$	98,184	$	22	$	(103	)	$	98,103

	Maturity (in years)	Amortized cost		Unrealized					Estimated fair value
				Gains		Losses
As of December 31, 2014
Corporate debt securities	2 or less	$	105,085	$	2	$	(167	)	$	104,920
Certificates of deposit	2 or less	14,600		—		—			14,600
Commercial paper	1 or less	2,895		1		—			2,896
Total		$	122,580	$	3	$	(167	)	$	122,416