Accounts Receivable (Factoring Activities) (Details) - USD ($) $ in Millions	12 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2015
Receivables [Abstract]
Receivables factored	$ 5,149	$ 3,314	$ 1,796
Factoring expense	16	19	$ 10
Factored receivables outstanding	$ 679	$ 626