FAIR VALUE OF FINANCIAL INSTRUMENTS (Tables)

3 Months Ended

Mar. 31, 2018

Fair Value Disclosures [Abstract]

Schedule of Financial Instruments Measured at Fair Value

The following table represents the Company’s financial instruments measured at fair value as of March 31, 2018 and December 31, 2017 (in thousands):

	March 31, 2018								December 31, 2017
	Level 1		Level 2		Level 3		Total		Level 1		Level 2		Level 3		Total
Cash Equivalents:
Money market funds	$	218,054	$	—	$	—	$	218,054	$	217,838	$	—	$	—	$	217,838
Commercial paper	—		9,985		—		9,985		—		46,927		—		46,927
Marketable Securities:
Commercial paper	—		227,619		—		227,619		—		138,412		—		138,412
Corporate bonds	—		89,672		—		89,672		—		69,926		—		69,926
Agency bonds	—		80,861		—		80,861		—		78,913		—		78,913
U.S. government bonds	—		38,609		—		38,609		—		—		—		—
Agency discount notes	—		—		—		—		—		10,989		—		10,989
Total cash equivalents and marketable securities	$	218,054	$	446,746	$	—	$	664,800	$	217,838	$	345,167	$	—	$	563,005