INVESTMENTS (Tables)

9 Months Ended

Sep. 30, 2014

Investments, Debt and Equity Securities [Abstract]

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

The following table summarizes the amortized cost and estimated fair value of our marketable securities, which are considered to be available-for-sale investments and included in short-term investments on the condensed consolidated balance sheets:

	Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
	(in thousands)
Balance as of September 30, 2014
Bank deposits	$	60,200	$	—	$	—		$	60,200
U.S. Treasury securities	70,181		5		(1		)	70,185
Corporate and municipal notes	307,919		21		(43		)	307,897
Total	$	438,300	$	26	$	(44	)	$	438,282
Balance as of December 31, 2013
Bank deposits	$	40,000	$	—	$	—		$	40,000
U.S. Treasury securities	67,648		6		(4		)	67,650
Corporate and municipal notes	362,561		173		(36		)	362,698
Total	$	470,209	$	179	$	(40	)	$	470,348