Business Segments and Enterprise-Wide Disclosures (Revenue Concentrations) (Details)	12 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Mar. 31, 2011
Customer Concentration Risk
Revenue, Major Customer [Line Items]
Number of customers providing 10% or more of total revenues	0		0
Customer Concentration Risk | HE
Revenue, Major Customer [Line Items]
Number of customers providing 10% or more of total revenues		1
Major customer percent of total revenues		11.00%
Customer Concentration Risk | Accounts Receivable | HE
Revenue, Major Customer [Line Items]
Major customer/supplier, percent of total	14.00%	16.00%
Number of major customers with concentration risk	1	1
Supplier Concentration Risk | Revenue | HE | Program Supplier 1
Revenue, Major Customer [Line Items]
Major customer/supplier, percent of total	10.00%	7.00%	10.00%
Supplier Concentration Risk | Revenue | HE | Program Supplier 2
Revenue, Major Customer [Line Items]
Major customer/supplier, percent of total	9.00%	10.00%	9.00%
Supplier Concentration Risk | Revenue | HE | Program Supplier 3
Revenue, Major Customer [Line Items]
Major customer/supplier, percent of total	6.00%	9.00%	10.00%