Income Taxes - Components Of Provision For Income Taxes Related To Continuing Operations (Details) - USD ($) $ in Millions	12 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2015
Current
Federal	$ 524	$ 658	$ 453
State	86	96	90
Foreign	122	90	101
Total current	732	844	644
Deferred
Federal	767	95	195
State	164	42	53
Foreign	(49)	(73)	(77)
Total deferred	882	64	171
Income tax expense	$ 1,614	$ 908	$ 815