Cash, Cash Equivalents and Short-term Investments (Tables)

9 Months Ended

Sep. 30, 2014

Cash and Cash Equivalents [Abstract]

Summary of Cash and Cash Equivalents and Short-Term Investments

Cash and cash equivalents and short-term investments consisted of the following as of September 30, 2014 and December 31, 2013 (in thousands):

September 30, 2014

	Amortized Cost		Unrealized Gains		Unrealized Losses			Estimated Fair Value
Description
Cash	$	98,287	$	—	$	—		$	98,287
Cash equivalents:
Money market mutual funds	635		—		—			635
Total cash and cash equivalents	98,922		—		—			98,922
Short-term investments:
Corporate bonds	47,938		60		(54		)	47,944
U.S. agency securities	39,267		36		(26		)	39,277
Asset-backed securities	22,035		12		(39		)	22,008
U.S. Treasury securities	15,740		44		(12		)	15,772
Total short-term investments	124,980		152		(131		)	125,001
Cash, cash equivalents and short-term investments	$	223,902	$	152	$	(131	)	$	223,923

December 31, 2013

	Amortized Cost		Unrealized Gains		Unrealized Losses			Estimated Fair Value
Description
Cash	$	169,968	$	—	$	—		$	169,968
Cash equivalents:
Money market mutual funds	164		—		—			164
Total cash and cash equivalents	170,132		—		—			170,132
Short-term investments:
Corporate bonds	40,503		90		(10		)	40,583
U.S. agency securities	31,720		40		(13		)	31,747
Asset-backed securities	15,880		14		(12		)	15,882
U.S. Treasury securities	16,742		50		(3		)	16,789
Total short-term investments	104,845		194		(38		)	105,001
Cash, cash equivalents and short-term investments	$	274,977	$	194	$	(38	)	$	275,133

Cost and Estimated Fair Value of Short-Term Fixed Income Securities

The following table summarizes the cost and estimated fair value of short-term fixed income securities classified as short-term investments based on stated maturities as of September 30, 2014:

	Amortized Cost		Estimated Fair Value
	(in thousands)
Less than 1 year	$	15,028	$	15,047
Due in 1 to 3 years	109,952		109,954
Total	$	124,980	$	125,001