FAIR VALUE MEASUREMENTS (Tables)

12 Months Ended

Dec. 31, 2015

FAIR VALUE MEASUREMENTS

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

        The following tables summarize the levels of the fair value hierarchy into which the Company's financial assets and liabilities 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

        The following table summarizes the levels of the fair value hierarchy into which the Company's financial assets fall as of December 31, 2014:

	Total		Level 1		Level 2		Level 3
Financial assets:
Included in cash and cash equivalents
Government securities money market	$	128,739	$	—	$	128,739	$	—
Investments
U.S. treasury bills		39,997		—		39,997		—
Total financial assets	$	168,736	$	—	$	168,736	$	—

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

	Convertible notes
January 1, 2015	$	—
Non-cash settlement of customer receivable		635
December 31, 2015	$	635
Unrealized gains (losses) related to investment still held as of December 31, 2015	$	—

	Common Stock
January 1, 2014	$	1,904
Non-cash settlement of customer receivable		1,000
Distribution to Parent		(2,904	)
December 31, 2014	$	—
Unrealized gains (losses) related to investment still held as of December 31, 2014	$	—