FAIR VALUE MEASUREMENTS (Tables)

9 Months Ended

Sep. 30, 2017

FAIR VALUE MEASUREMENTS

Summary of the levels of the fair value hierarchy into which the Company's financial assets fall

The following table summarizes the levels of the fair value hierarchy into which the Company’s financial assets fall as of September 30, 2017:

	Total		Level 1		Level 2		Level 3
Financial assets:
Included in cash and cash equivalents
Government debt securities (1)	$	14,487	$	—	$	14,487	$	—
Government securities money market		53,842		—		53,842		—
Investments
Government debt securities (1)		54,258		—		54,258		—
U.S. treasury instruments		61,864		61,864		—		—
Common stock		244		244		—		—
Total financial assets	$	184,695	$	62,108	$	122,587	$	—

(1) Consists of municipal bonds, agency bonds and agency discount notes.

The following table summarizes the levels of the fair value hierarchy into which the Company’s financial assets fall as of December 31, 2016:

	Total		Level 1		Level 2		Level 3
Financial assets:
Included in cash and cash equivalents
U.S. treasury bills	$	44,999	$	—	$	44,999	$	—
Government securities money market		201,934		—		201,934		—
Investments
U.S. treasury bills		32,995		—		32,995		—
Convertible notes		388		388		—		—
Total financial assets	$	280,316	$	388	$	279,928	$	—