FAIR VALUE MEASUREMENTS (Tables)

9 Months Ended

Sep. 30, 2018

Fair Value Disclosures [Abstract]

Assets Measured and Carried at Fair Value

The tables below present information about the Company’s financial assets that are measured and carried at fair value and indicate the level within the fair value hierarchy of valuation techniques it utilizes to determine such fair value: 

	Fair Value Measurement as of September 30, 2018
	Total		Level 1		Level 2		Level 3
	(in thousands)
Assets
Money market funds	$	85,321	$	85,321	$	—	$	—
Commercial paper		89,795		—		89,795		—
Government and government agency bonds		510,028		510,028		—		—
Corporate bonds		83,261		83,261		—		—
Strategic investment		30,000		—		—		30,000
Certificates of deposit		1,001		1,001		—		—
Total	$	799,406	$	679,611	$	89,795	$	30,000

	Fair Value Measurement as of December 31, 2017
	Total		Level 1		Level 2		Level 3
	(in thousands)
Assets
Money market funds	$	352,370	$	352,370	$	—	$	—
Commercial paper		133,368		—		133,368		—
Government and government agency bonds		294,717		284,745		9,972		—
Corporate bonds		127,956		127,956		—		—
Certificates of deposit		648		648		—		—
Total	$	909,059	$	765,719	$	143,340	$	—