Restructuring And Impairment Costs (Narrative) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended			3 Months Ended	12 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Mar. 31, 2012 Termination Of Business Arrangements With Supplier And Processor [Member]	Dec. 31, 2010 Canadian Operations [Member]	Mar. 31, 2011 Canadian Operations [Member]
Restructuring Cost and Reserve [Line Items]
Impairment charge - property, plant, and equipment	$ 0	$ 0		$ 5,600
Employee termination benefits					2,400
Pension curtailment and settlement costs					4,100
Other restructuring costs			$ 3,100