FAIR VALUE MEASUREMENTS (Tables)

9 Months Ended

Sep. 30, 2015

Fair Value Disclosures [Abstract]

Financial Assets Measured at Fair Value

Fair values determined by Level 3 inputs are unobservable data points for the asset or liability, and includes situations where there is little, if any, market activity for the asset or liability.

Description    (in thousands)	September 30, 2015		Quoted Prices in Active Markets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Assets:
Money Market Funds	$	108,904	$	108,904	$	—	$	—
US Treasury Bills and Notes	191,698		—		191,698		—
Total	$	300,602	$	108,904	$	191,698	$	—

Description   (in thousands)	December 31, 2014		Quoted Prices in Active Markets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Assets:
Money Market Funds	$	15,610	$	15,610	$	—	$	—
US Treasury Bills and Notes	165,260		—		165,260		—
Total	$	180,870	$	15,610	$	165,260	$	—

Marketable Securities

The following tables summarize the Company’s marketable securities at September 30, 2015, and December 31, 2014:

	September 30, 2015
Description  (in thousands)	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
US Treasury Bills and Notes (due within 1 year)	$	93,548	$	26	$	—	$	93,574
US Treasury Bills and Notes (due after 1 year through 2 years)	98,068		56		—		98,124
Total	$	191,616	$	82	$	—	$	191,698

	December 31, 2014
Description  (in thousands)	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
US Treasury Bills and Notes (due within 1 year)	$	165,232	$	28	$	—	$	165,260
Total	$	165,232	$	28	$	—	$	165,260