Installment Receivables (Details) - USD ($) $ in Millions	6 Months Ended
	Sep. 30, 2015	Mar. 31, 2015
Accounts, Notes, Loans and Financing Receivable [Line Items]
Installment Billing Maximum Payment Term	24 months
Installment receivables, gross	$ 1,387	$ 1,725
Deferred interest	(96)	(139)
Installment receivables, net of deferred interest	1,291	1,586
Allowance for credit losses	(178)	(190)
Installment receivables, net	1,113	1,396
Accounts and notes receivable, net
Accounts, Notes, Loans and Financing Receivable [Line Items]
Installment receivables, net	929	1,035
Other Assets
Accounts, Notes, Loans and Financing Receivable [Line Items]
Installment receivables, net	$ 184	$ 361