Marketable Securities

6 Months Ended

Jun. 30, 2011

D. Marketable Securities

A summary of the Company's cash, cash equivalents and marketable securities is shown below:

		Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value

		(in thousands)
June 30, 2011
Cash and cash equivalents
	Cash and money market funds	$	422,289	$	—	$	—		$	422,289
	Government-sponsored enterprise securities		35,905		1		—			35,906

Total cash and cash equivalents		$	458,194	$	1	$	—		$	458,195

Marketable securities
	U.S. Treasury securities (due within 1 year)	$	9,546	$	1	$	—		$	9,547
	Government-sponsored enterprise securities (due within 1 year)		125,739		10		—			125,749

Total marketable securities		$	135,285	$	11	$	—		$	135,296

Total cash, cash equivalents and marketable securities		$	593,479	$	12	$	—		$	593,491

December 31, 2010
Cash and cash equivalents
	Cash and money market funds	$	193,845	$	—	$	—		$	193,845
	U.S. Treasury securities		4,770		—		—			4,770
	Government-sponsored enterprise securities		44,587		1		(6	)		44,582

Total cash and cash equivalents		$	243,202	$	1	$	(6	)	$	243,197

Marketable securities
	U.S. Treasury securities (due within 1 year)	$	103,230	$	1	$	(11	)	$	103,220
	Government-sponsored enterprise securities (due within 1 year)		684,969		87		(62	)		684,994

Total marketable securities		$	788,199	$	88	$	(73	)	$	788,214

Total cash, cash equivalents and marketable securities		$	1,031,401	$	89	$	(79	)	$	1,031,411

In the three months ended June 30, 2011 and 2010, the Company had proceeds of $251.7 million and $333.9 million, respectively, from sales and maturities of available-for-sale securities. In the six months ended June 30, 2011 and 2010, the Company had proceeds of $788.0 million and $518.1 million, respectively, from sales and maturities of available-for-sale securities.

Realized gains and losses are determined using the specific identification method and are included in interest income on the Company's condensed consolidated statements of operations. There were no gross realized gains and losses for the three and six months ended June 30, 2011 and 2010.

- Definition

This item represents the entire disclosure related to Available-for-sale Securities which consist of all investments in certain debt and equity securities neither classified as trading or held-to-maturity securities. A debt security represents a creditor relationship with an enterprise. Debt securities include, among other items, US Treasury securities, US government securities, municipal securities, corporate bonds, convertible debt, commercial paper, and all securitized debt instruments. An equity security represents an ownership interest in an enterprise or the right to acquire or dispose of an ownership interest in an enterprise at fixed or determinable prices. Equity securities include, among other things, common stock, certain preferred stock, warrant rights, call options, and put options, but do not include convertible debt. An entity may opt to provide the reader with additional narrative text to better understand the nature of investments in debt and equity securities which are categorized as Available-for-sale.

+ References+ Details