INVESTMENTS

9 Months Ended

Sep. 30, 2014

Investments, Debt and Equity Securities [Abstract]

INVESTMENTS

INVESTMENTS

Marketable Securities

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

Certain short-term debt securities with original maturities of less than 90 days are included in cash and cash equivalents on the condensed consolidated balance sheets and are not included in the tables above. In addition, certificates of deposit of $15.0 million and $17.2 million as of September 30, 2014 and December 31, 2013, respectively, were included within short-term investments in the condensed consolidated balance sheets but are excluded from the tables above as they were not deemed to be securities.