FAIR VALUE MEASUREMENTS (Tables)

6 Months Ended

Jun. 30, 2018

Fair value of marketable securities and investments

The fair-value hierarchy of the Company's cash equivalents and marketable securities at June 30, 2018, and December 31, 2017, was as follows:



	Fair Value Measurement at
	June 30, 2018
(In thousands)	Total Fair Value		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)
Corporate securities	$	89,265	$	—	$	89,265
Commercial paper	128,809		—		128,809
Government securities	9,229		—		9,229
Money market funds	467		467		—
Total	$	227,770	$	467	$	227,303



	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

- Definition

Tabular disclosure of financial instruments measured at fair value, including those classified in shareholders' equity measured on a recurring or nonrecurring basis. Disclosures include, but are not limited to, fair value measurements recorded and the reasons for the measurements, level within the fair value hierarchy in which the fair value measurements are categorized and transfers between levels 1 and 2. Nonrecurring fair value measurements are those that are required or permitted in the statement of financial position in particular circumstances.

+ References + Details