Fair Value of Financial Instruments (Tables)

3 Months Ended

Mar. 31, 2015

Fair Value Disclosures [Abstract]

Financial instruments measured at fair value by level within the fair value hierarchy

The following table sets forth our financial instruments that were measured at fair value by level within the fair value hierarchy (in thousands):

	March 31, 2015								December 31, 2014
	Level I		Level II		Level III		Total		Level I		Level II		Level III		Total
Assets
Money market funds	$	15,898	$	—	$	—	$	15,898	$	10,220	$	—	$	—	$	10,220
U.S. government and agency securities	—		97,932		—		97,932		—		109,087		—		109,087
Total assets measured at fair value	$	15,898	$	97,932	$	—	$	113,830	$	10,220	$	109,087	$	—	$	119,307

Summary of investments

The following is a summary of investments at March 31, 2015 and December 31, 2014 (in thousands):

	March 31, 2015
	Amortized Cost		Gross Unrealized Gain		Gross Unrealized Loss			Estimated Fair Value
U.S. government and agency securities	$	97,926	$	12	$	(6	)	$	97,932

	December 31, 2014
	Amortized Cost		Gross Unrealized Gain		Gross Unrealized Loss			Estimated Fair Value
U.S. government and agency securities	$	109,136	$	3	$	(52	)	$	109,087

Summary of cash and cash equivalents

The following is a summary of our cash and cash equivalents (in thousands):

	March 31, 2015		December 31, 2014
Cash	$	21,084	$	23,493
Money market funds	15,898		10,220
Cash and cash equivalents	$	36,982	$	33,713