Fair Value of Financial Instruments (Tables)

3 Months Ended

Jun. 30, 2012

Fair Value Of Financial Instruments [Abstract]

Schedule Of Fair Value Of Financial Assets

	Quoted Prices
	in Active		Significant
	Markets for		Other		Significant
	Identical		Observable		Unobservable
	Assets		Inputs		Inputs
	Level 1		Level 2		Level 3		Total
Cash equivalents
Money market funds	$	58,138	$	-	$	-	$	58,138
Commercial paper		-		18,778		-		18,778
	$	58,138	$	18,778	$	-	$	76,916
Available-for-sale securities
Corporate debt securities	$	-	$	32,563	$	-	$	32,563
U.S. Treasury securities		16,762		-		-		16,762
Agency discount notes		-		17,032		-		17,032
Commercial paper		-		16,002		-		16,002
	$	16,762	$	65,597	$	-	$	82,359

	Quoted Prices
	in Active		Significant
	Markets for		Other		Significant
	Identical		Observable		Unobservable
	Assets		Inputs		Inputs
	Level 1		Level 2		Level 3		Total
Cash equivalents
Money market funds	$	40,557	$	-	$	-	$	40,557
Commercial paper		-		15,952		-		15,952
Corporate debt securities		-		1,112		-		1,112
	$	40,557	$	17,064	$	-	$	57,621
Available-for-sale securities
Corporate debt securities	$	-	$	48,025	$	-	$	48,025
U.S. Treasury securities		30,261		-		-		30,261
Agency discount notes		-		16,796		-		16,796
Commercial paper		-		23,709		-		23,709
	$	30,261	$	88,530	$	-	$	118,791