Segment, Geographical Area, Major Customer and Major Supplier Information (3 Largest Customers) (Details)	12 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2013
Rexam Plc [Member]
Revenue, Major Customer [Line Items]
Percentage of total net sales	18.00%	17.00%	15.00%
Affiliates of Ball Corporation [Member]
Revenue, Major Customer [Line Items]
Percentage of total net sales	10.00%	10.00%	10.00%
Anheuser-Busch LLC [Member]
Revenue, Major Customer [Line Items]
Percentage of total net sales	7.00%	8.00%	11.00%
Beverage and Food Can [Member] | Sales Revenue [Member]
Revenue, Major Customer [Line Items]
Percentage of total net sales	56.00%	55.00%	55.00%
Automotive Products [Member] | Sales Revenue [Member]
Revenue, Major Customer [Line Items]
Percentage of total net sales	13.00%	11.00%	8.00%