INVESTMENTS (Tables)

9 Months Ended

Sep. 30, 2013

INVESTMENTS

Amortized cost and estimated fair value of marketable securities, which are considered to be available-for-sale investments

	Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
	(in thousands)
Balance as of September 30, 2013
Bank deposits	$	20,000	$	—	$	—		$	20,000
U.S. Treasury securities	75,021		18		—			75,039
Corporate and municipal notes	352,099		86		(55		)	352,130
Total	$	447,120	$	104	$	(55	)	$	447,169
Balance as of December 31, 2012
Bank deposits	$	61,000	$	—	$	—		$	61,000
U.S. Treasury securities	114,041		4		(3		)	114,042
Corporate and municipal notes	640,234		158		(215		)	640,177
Total	$	815,275	$	162	$	(218	)	$	815,219

Contractual maturities of marketable securities

	September 30, 2013				December 31, 2012
	Amortized Cost		Fair  Value		Amortized Cost		Fair Value
	(in thousands)
Within 1 year	$	370,450	$	370,530	$	812,104	$	812,052
1-2 years	76,670		76,639		3,171		3,167
Total	$	447,120	$	447,169	$	815,275	$	815,219