Segment, Geographical Area, Major Customer and Major Supplier Information (3 Largest Customers) (Details) - Net sales [Member]	12 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2015
Ball [Member]
Revenue, Major Customer [Line Items]
Percentage of total net sales	27.00%	30.00%	28.00%
Ford [Member]
Revenue, Major Customer [Line Items]
Percentage of total net sales	10.00%	4.00%	2.00%
Beverage and Food Can Products [Member]
Revenue, Major Customer [Line Items]
Percentage of total net sales	52.00%	55.00%	56.00%
Automotive Products [Member]
Revenue, Major Customer [Line Items]
Percentage of total net sales	23.00%	20.00%	13.00%