Related Party Balances and Transactions (Details) - USD ($) $ in Millions	1 Months Ended	12 Months Ended
	Mar. 31, 2018	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016
Investee
Related Party Transaction [Line Items]
Revenue from related parties		$ 154	$ 112	$ 112
Accounts receivable, related parties, current	$ 15	15	$ 12
Selling, Distribution and Administrative Expenses | California Foundation
Related Party Transaction [Line Items]
Pre-tax charitable contribution expense	100
After-tax charitable contribution expense	64
Other accrued liabilities | California Foundation
Related Party Transaction [Line Items]
Pledge payable balance	$ 100	$ 100