Fair Value Measurements (Tables)

3 Months Ended

Mar. 31, 2014

Fair Value Disclosures [Abstract]

Cash Equivalents and Marketable Securities Measured at Fair Value on a Recurring Basis

The following table summarizes the cash equivalents and marketable securities measured at fair value on a recurring basis as of March 31, 2014 (in thousands):

	Level 1		Level 2		Level 3		Total
Cash equivalents	$	28,816	$	960	$	—	$	29,776
Marketable securities:
Certificates of deposit		—		6,716		—		6,716
U.S. Treasuries		127,721		—		—		127,721
	$	156,537	$	7,676	$	—	$	164,213

The following table summarizes the cash equivalents and marketable securities measured at fair value on a recurring basis as of December 31, 2013 (in thousands):

	Level 1		Level 2		Level 3		Total
Cash equivalents	$	68,792	$	—	$	—	$	68,792
Marketable securities:
Certificates of deposit		—		6,915		—		6,915
U.S. Treasuries		115,419		—		—		115,419
	$	184,211	$	6,915	$	—	$	191,126