Asset Impairment Charges (Details) (USD $) In Thousands, unless otherwise specified	1 Months Ended	12 Months Ended
	Aug. 31, 2011	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2012
Finite-Lived Intangible Assets [Line Items]
Impairment of intangible assets (excluding goodwill)			$ 1,729
Supplier contract termination notice period	24 months
Asset impairment charges		0	1,729	4,250
Liquid CO2 Plant [Member]
Finite-Lived Intangible Assets [Line Items]
Asset impairment charges				2,500
Air Separation Unit [Member]
Finite-Lived Intangible Assets [Line Items]
Asset impairment charges				$ 1,800