Accounts Receivable Discount Programs (Details) (USD $)	6 Months Ended
	Sep. 30, 2012	Sep. 30, 2011
Accounts Receivable Discount Programs [Abstract]
Receivables discounted	$ 157,335,000	$ 133,222,000
Weighted average days	316 days	312 days
Annualized weighted average discount rate (in hundredths)	2.80%	2.90%
Amount of discount as interest expense	$ 3,824,000	$ 3,363,000