Long-Term Obligations (Narrative) (Details) (USD $)			12 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Mar. 31, 2013 Minimum [Member]	Mar. 31, 2013 Maximum [Member]	Mar. 31, 2013 Interest Rate Swap Agreements [Member]	Mar. 31, 2012 Interest Rate Swap Agreements [Member]	Mar. 31, 2011 Interest Rate Swap Agreements [Member]	Mar. 31, 2013 Long-term Debt [Member]
Debt Instrument [Line Items]
Medium-term notes maturity date			October 15, 2013	December 1, 2014
Medium-term notes interest rate, percentage			5.20%	6.25%
Fully funded amortizing term loan	$ 100,000,000
Interest rate, term loan								2.91%
Long-term debt	181,250,000	392,500,000					245,000,000
Derivative liability value					1,700,000
Notional amount of interest rate cash flow hedge derivatives	93,000,000				92,500,000	98,800,000
Long-term debt maturities, 2014	211,000,000
Long-term debt maturities, 2015	116,000,000
Long-term debt maturities, 2016	28,000,000
Long-term debt maturities, 2017	$ 38,000,000