FAIR VALUE MEASUREMENTS (Tables)

12 Months Ended

Dec. 31, 2017

Fair Value Disclosures [Abstract]

Fair Value Of Marketable Securities and Investments [Table Text Block]

The fair value hierarchy of the Company’s cash equivalents and marketable securities at December 31, 2017, and December 31, 2016, was as follows:

	Fair Value Measurement at
	December 31, 2017
(in thousands)	Total Fair Value		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)
Corporate securities	$	179,951	$	—	$	179,951
Commercial paper	51,122		—		51,122
Government securities	9,285		—		9,285
Money market funds	195		195		—
Total	$	240,553	$	195	$	240,358

	Fair Value Measurement at
	December 31, 2016
(in thousands)	Total Fair Value		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)
Corporate securities	$	132,141	$	—	$	132,141
Commercial paper	58,031		—		58,031
Money market funds	1,916		1,916		—
Total	$	192,088	$	1,916	$	190,172