FAIR VALUE (Tables)

6 Months Ended

Jun. 30, 2017

Summary of fair value hierarchy for its financial assets and liabilities measured at fair value on a recurring basis

The following table represents the Company's fair value hierarchy for its financial assets (cash equivalents and investments) measured at fair value on a recurring basis as of June 30, 2017 (in thousands):



	Level 1		Level 2		Level 3		Total
Assets:
Money market funds	$	320,826	$	—	$	—	$	320,826
Commercial paper	11,096		—		—		11,096
Auction rate securities	—		—		9,952		9,952
Total assets measured at fair value	$	331,922	$	—	$	9,952	$	341,874

The following table represents the Company's fair value hierarchy for its financial assets (cash equivalents and investments) measured at fair value on a recurring basis as of December 31, 2016 (in thousands):



	Level 1		Level 2		Level 3		Total
Assets:
Money market funds	$	175,344	$	—	$	—	$	175,344
Commercial paper	6,383		—		—		6,383
Auction rate securities	—		—		9,952		9,952
Total assets measured at fair value	$	181,727	$	—	$	9,952	$	191,679

Summary of changes in the fair value of the company's level 3 assets

The following tables summarize changes in fair value of the Company’s Level 3 assets for the three and six months ended June 30, 2017 and 2016 (in thousands):



	Three Months Ended June 30,				Six Months Ended June 30,
	2017		2016		2017		2016
Balance at beginning of period	$	9,952	$	11,036	$	9,952	$	15,507
Decrease in unrealized loss included in accumulated other comprehensive loss	—		—		—		229
Settlements	—		—		—		(4,700		)
Balance at end of period	$	9,952	$	11,036	$	9,952	$	11,036

The following table summarizes changes in fair value of the Company’s Level 3 assets from December 31, 2015 to June 30, 2017 (in thousands):



	Auction Rate Securities
Balance at December 31, 2015	$	15,507
Decrease in unrealized loss included in accumulated other comprehensive loss	395
Settlements	(5,950		)
Balance at December 31, 2016	9,952
Decrease in unrealized loss included in accumulated other comprehensive loss	—
Settlements	—
Balance at June 30, 2017	$	9,952