Indebtedness (Money Market Loans Narrative) (Details) (USD $)			9 Months Ended
	Dec. 31, 2011	Mar. 31, 2011	Dec. 31, 2011 Agreement Expiring In January 2012 [Member]	Dec. 31, 2011 Agreement Expiring In February 2012 [Member]
Debt Instrument [Line Items]
Money market loans maximum amount allowed			$ 35,000,000	$ 35,000,000
Money market advances agreement expiration			January 2, 2013	April 1, 2012
Money market loans, terms			The advances may be for one to six months with rates at a fixed spread over the corresponding LIBOR	generally overnight or for up to seven days
Short-term advances outstanding			0	0
Money market loan advances, amount outstanding	$ 406,861,000	$ 0