Fair Value Measurements (Tables)

6 Months Ended

Sep. 30, 2011

Fair Value Measurements [Abstract]

Schedule Of Financial Assets And Liabilities

	Total Fair Value			Level I		Level II			Level III
ASSETS:
Cash and cash equivalents	$	103,859		$	103,859	$	0		$	0
U.S. government and municipal obligations		25,581			25,581		0			0
Commercial paper		25,082			0		25,082			0
Corporate bonds		25,758			25,758		0			0
Certificate of deposits		1,255			0		1,255			0
Auction rate securities		17,372			0		0			17,372
Derivative financial instruments		18			0		18			0
	$	198,925		$	155,198	$	26,355		$	17,372
LIABILITIES:
Derivative financial instruments	$	(412	)	$	0	$	(412	)	$	0
	$	(412	)	$	0	$	(412	)	$	0

Reconciliation Of Changes In Fair Value Of Level III Financial Assets

	Three Months Ended September 30, 2011		Six Months Ended September 30, 2011
Balance at beginning of period	$	17,248	$	17,482
Change in accrued interest receivable		12		(17	)
Redemptions		0		(250	)
Reversal of temporary loss on redeemed securities		0		45
Unrealized gains included in other comprehensive income		112		112
Balance at end of period	$	17,372	$	17,372