Supplemental Financial Information (Details) (USD $)	12 Months Ended
	Mar. 31, 2011	Mar. 31, 2010	Mar. 31, 2009
Notes to Financial Statements [Abstract]
Cash paid for income taxes	$ 17,000,000	$ 9,800,000	$ 8,800,000
Cash paid for interest on borrowings	24,400,000	24,400,000	24,400,000
Allowance for Doubtful Accounts [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Balances at Beginning of Year	3,109,000	3,176,000	3,152,000
Charged to Cost and Expense	31,000	90,000	132,000
Deductions	(302,000)	(157,000)	(108,000)
Balance at End of Year	$ 2,838,000	$ 3,109,000	$ 3,176,000