Risk Management Activities and Financial Instruments (Details 4) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Mar. 31, 2013
Risk management activities and financial instruments
Fiscal year ending March 31, 2014	$ 5,128
Fiscal year ending March 31, 2015	3,910
Fiscal year ending March 31, 2016	351
Thereafter	269
Total	9,658	3,173
Energy Contracts
Risk management activities and financial instruments
Fiscal year ending March 31, 2014	5,141
Fiscal year ending March 31, 2015	3,870
Fiscal year ending March 31, 2016	307
Thereafter	244
Total	9,562
Currency contracts
Risk management activities and financial instruments
Fiscal year ending March 31, 2014	(13)
Fiscal year ending March 31, 2015	40
Fiscal year ending March 31, 2016	44
Thereafter	25
Total	$ 96