Investments

12 Months Ended

Dec. 31, 2011

Investments [Abstract]

Investments

2. Investments

Investments consisted of available-for-sale securities as follows (in thousands):

	Amortized cost		Gross unrealized gains		Gross unrealized losses			Fair value
December 31, 2011
U.S. Treasury securities	$	228,001	$	24	$	(3	)	$	228,022
Corporate obligations		9,565		0		(1	)		9,564
Auction rate securities		5,780		0		0			5,780
Total	$	243,346	$	24	$	(4	)	$	243,366
Contractual Maturities
Due in one year or less	$	237,566						$	237,586
Due in 2017		5,780							5,780
Total	$	243,346						$	243,366
	Amortized cost		Gross unrealized gains		Gross unrealized losses			Fair value
December 31, 2010
U.S. Treasury securities	$	249,580	$	10	$	(11	)	$	249,579
Corporate obligations		11,358		48		0			11,406
Auction rate securities		14,450		0		(1,419	)		13,031
Total	$	275,388	$	58	$	(1,430	)	$	274,016
Contractual Maturities
Due in one year or less	$	260,938						$	260,985
Due in 2017		14,450							13,031
Total	$	275,388						$	274,016

Investments are presented in the accompanying consolidated balance sheets as follows (in thousands):

	December 31,
	2011		2010
Short-term investments	$	243,062	$	260,682
Long-term investments		0		13,031
Other non-current assets		304		303
Total	$	243,366	$	274,016

The aggregate estimated fair value of the Company's investments with unrealized losses was as follows (in thousands):

	Period of continuous unrealized loss
	12 Months or less					Greater than 12 months
	Fair value		Gross unrealized losses			Fair value		Gross unrealized losses
December 31, 2011
U.S. Treasury securities	$	80,234	$	(3	)	$	NA	$	NA
Corporate obligations		4,571		(1	)		NA		NA
Total	$	84,805	$	(4	)	$	NA	$	NA
December 31, 2010
U.S. Treasury securities	$	122,581	$	(11	)	$	NA	$	NA
Auction rate securities		NA		NA			13,031		(1,419	)
Total	$	122,581	$	(11	)	$	13,031	$	(1,419	)