Fair Value of Financial Instruments (Tables)

12 Months Ended

Dec. 31, 2016

Fair Value Disclosures [Abstract]

Schedule of Fair Value of Cash Equivalents and Marketable Securities

The following tables present the fair value of cash equivalents and marketable securities in accordance with the hierarchy discussed in Note 2 (in thousands):

	Quoted		Significant
	prices		other		Significant
	in active		observable		unobservable
	markets		inputs		inputs
	(Level 1)		(Level 2)		(Level 3)		Total
December 31, 2016
Money market mutual funds (cash equivalents)	$	—	$	24,840	$	—	$	24,840
Corporate bonds (marketable securities)		—		133,208		—		133,208
Common equity securities (marketable securities)		918		—		—		918
	$	918	$	158,048	$	—	$	158,966

	Quoted		Significant
	prices		other		Significant
	in active		observable		unobservable
	markets		inputs		inputs
	(Level 1)		(Level 2)		(Level 3)		Total
December 31, 2015
Money market mutual funds (cash equivalents)	$	—	$	54,104	$	—	$	54,104
Corporate bonds (marketable securities)		—		157,222		—		157,222
Commercial paper (marketable securities)		—		4,990		—		4,990
Common equity securities (marketable securities)		39		—		—		39
	$	39	$	216,316	$	—	$	216,355