Short-term Investments (Tables)

3 Months Ended

Mar. 31, 2012

Short-term Investments [Abstract]

Schedule Of Summary Of Short-Term Investments

The following is a summary of short-term investments as of March 31, 2012 and December 31, 2011 (in thousands):

	Available-for-Sale Securities
	Amortized Cost		Gross Unrealized Gains (1)		Gross Unrealized Losses (1)			Estimated Fair Value
March 31, 2012
Obligations of U.S. Government-sponsored enterprises	$	60,758	$	8	$	(26	)	$	60,740
Corporate debt securities	169,378		1,145		(38		)	170,485
Total	$	230,136	$	1,153	$	(64	)	$	231,225
December 31, 2011
Obligations of U.S. Government-sponsored enterprises	$	40,914	$	3	$	(45	)	$	40,872
Corporate debt securities	62,466		890		(22		)	63,334
Total	$	103,380	$	893	$	(67	)	$	104,206

(1) The unrealized gains on investments in available-for-sale securities, net of tax effects were $0.7 million and $0.5 million at March 31, 2012 and December 31, 2011, respectively. Additionally, other comprehensive loss included unrealized losses, net of tax effects of $0.7 million and $1.8 million, on investments underlying our 2001 Non-Qualified Deferred Compensation Plan at March 31, 2012 and December 31, 2011, respectively.

Schedule Of Contractual Maturities Of Short-Term Investments

Contractual maturities of short-term investments at March 31, 2012 were as follows (in thousands):

	Fair Value
Due within 1 year	$	160,149
After 1 but within 5 years	68,799
After 5 but within 10 years	—
After 10 years	2,277
Total	$	231,225

Schedule Of Gross Unrealized Losses And Fair Value Of Investments

The following table shows the gross unrealized losses and fair value of our investments with unrealized losses that are not deemed to be other-than-temporarily impaired, aggregated by investment category and length of time that individual securities have been in a continuous unrealized loss position, at March 31, 2012 (in thousands):

	Less than 12 Months					12 Months or Greater					Total
	Fair Value		Unrealized Losses			Fair Value		Unrealized Losses			Fair Value		Unrealized Losses
Obligations of U.S Government-sponsored enterprises	$	19,960	$	(18	)	$	1,855	$	(8	)	$	21,815	$	(26	)
Corporate debt securities	52,524		(38		)	—		—			52,524		(38		)
	$	72,484	$	(56	)	$	1,855	$	(8	)	$	74,339	$	(64	)