FAIR VALUE MEASUREMENTS (Tables)

6 Months Ended

Jun. 30, 2013

FAIR VALUE MEASUREMENTS

Schedule of available-for-sale securities measured at fair value on a recurring basis

	Estimated Fair Value Measurements at Reporting Date Using
Types of Instruments	Quoted Prices in Active Markets for Identical Assets			Significant Other Observable Inputs		Significant Unobservable Inputs
(in thousands)	Level 1			Level 2		Level 3		Total
Cash and cash equivalents and available-for-sale securities at June 30, 2013:
Cash and money market funds	$	124,713		$	—	$	—	$	124,713
U.S. Treasury securities	233,542			—		—		233,542
Total	358,255			—		—		358,255
Less amounts classified as cash equivalents	(124,713		)	—		—		(124,713		)
Total available-for-sale securities	$	233,542		$	—	$	—	$	233,542
Cash and cash equivalents and available-for-sale securities at December 31, 2012:
Cash and money market funds	$	58,605		$	—	$	—	$	58,605
U.S. Treasury securities	155,981			—		—		155,981
Total	214,586			—		—		214,586
Less amounts classified as cash equivalents	(58,605		)	—		—		(58,605		)
Total available-for-sale securities	$	155,981		$	—	$	—	$	155,981