Fair Value of Financial Instruments (Tables)

6 Months Ended

Jun. 30, 2016

Fair Value Disclosures [Abstract]

Assets Measured or Disclosed at Fair Value on Recurring Basis

Assets measured or disclosed at fair value on a recurring basis as of June 30, 2016 and December 31, 2015 are summarized below:

	Fair Value Measurements Using
	Level 1		Level 2		Level 3		Total
	(in thousands)
June 30, 2016
Assets:
Cash and cash equivalents	$	46,177	$	—	$	—	$	46,177
Certificates of deposit		—		19,063		—		19,063
U.S. Government debt securities		—		111,037		—		111,037
Corporate debt securities		—		12,372		—		12,372
	$	46,177	$	142,472	$	—	$	188,649

	Fair Value Measurements Using
	Level 1		Level 2		Level 3		Total
	(in thousands)
December 31, 2015
Assets:
Cash and cash equivalents	$	49,778	$	—	$	—	$	49,778
Certificates of deposit		—		21,505		—		21,505
U.S. Government debt securities		—		46,276		—		46,276
Corporate debt securities		—		20,895		—		20,895
	$	49,778	$	88,676	$	—	$	138,454