FAIR VALUE MEASUREMENTS (Tables)

9 Months Ended

Sep. 30, 2016

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, 2016:

	Total		Level 1		Level 2		Level 3
Financial assets:
Included in cash and cash equivalents
U.S. treasury bills	$	112,485	$	42,487	$	69,998	$	—
Government securities money market		41,676		—		41,676		—
Investments
U.S. treasury bills		32,976		—		32,976		—
Common stock		530		530		—		—
Total financial assets	$	187,667	$	43,017	$	144,650	$	—

The following table summarizes the levels of the fair value hierarchy into which the Company’s financial assets fall as of December 31, 2015:

	Total		Level 1		Level 2		Level 3
Financial assets:
Included in cash and cash equivalents
U.S. treasury bills	$	100,996	$	71,998	$	28,998	$	—
Government securities money market		77,876		—		77,876		—
Investments
U.S. treasury bills		37,989		19,990		17,999		—
Convertible notes		635		—		—		635
Total financial assets	$	217,496	$	91,988	$	124,873	$	635

Schedule of changes to the Company's investment classified as Level 3

	Convertible notes
January 1, 2016	$	635
Unrealized gains (losses) included in accumulated other comprehensive income		22
March 31, 2016		657
Unrealized gains (losses) included in accumulated other comprehensive income		21
June 30, 2016		678
Transfer out of level 3 due to conversion of convertible notes to common stock		(678)
September 30, 2016	$	—