Investment in and Advances to Non-Consolidated Affiliates and Related Party Transactions (Period-end Account Balances with Non-consolidated Affiliates) (Details) - USD ($) $ in Millions	12 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Related Party Transaction [Line Items]
Accounts receivable - related parties	$ 60	$ 59
Other long-term assets-related parties	15	16
Accounts payable-related parties	51	48
Parent Company [Member]
Related Party Transaction [Line Items]
Accounts receivable - related parties		1
Related Party Transaction, Purchases from Related Party	3	5
Loans [Member]
Related Party Transaction [Line Items]
Loans and Leases Receivable, Related Parties, Additions	3
Equity Method Investee [Member]
Related Party Transaction [Line Items]
Accounts receivable - related parties	60	59
Other long-term assets-related parties	15	16
Accounts payable-related parties	$ 51	$ 48