FAIR VALUE OF FINANCIAL INSTRUMENTS (Tables)

9 Months Ended

Sep. 30, 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 September 30, 2018 and December 31, 2017 (in thousands):

	September 30, 2018								December 31, 2017
	Level 1		Level 2		Level 3		Total		Level 1		Level 2		Level 3		Total
Cash Equivalents:
Money market funds	$	219,742	$	—	$	—	$	219,742	$	217,838	$	—	$	—	$	217,838
Commercial paper	—		37,417		—		37,417		—		46,927		—		46,927
Marketable Securities:
Commercial paper	—		158,506		—		158,506		—		138,412		—		138,412
Corporate bonds	—		137,967		—		137,967		—		69,926		—		69,926
U.S. government bonds	—		69,208		—		69,208		—		—		—		—
Agency bonds	—		48,047		—		48,047		—		78,913		—		78,913
Agency discount notes	—		—		—		—		—		10,989		—		10,989
Total cash equivalents and marketable securities	$	219,742	$	451,145	$	—	$	670,887	$	217,838	$	345,167	$	—	$	563,005