Redeemable Noncontrolling Interests and Noncontrolling Interests - Schedule of Changes in Redeemable Noncontrolling Interests and Noncontrolling Interests (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017
Noncontrolling Interests
Beginning balance			$ 253
Net income attributable to noncontrolling interests	$ 57	$ 58	169	$ 169
Other comprehensive income (loss)	(11)		(55)
Ending balance	204		204
Redeemable Noncontrolling Interests
Beginning balance			1,459
Other comprehensive income (loss)	(11)		(55)
Ending balance	1,404		1,404
Noncontrolling Interest
Noncontrolling Interests
Beginning balance			253	178
Net income attributable to noncontrolling interests			135	137
Other comprehensive income (loss)			0	0
Payments of noncontrolling interests				(73)
Payments to noncontrolling interests			(143)
Exercises of Put Right				0
Other			(41)	(4)
Ending balance	204	238	204	238
Redeemable Noncontrolling Interests
Other comprehensive income (loss)			0	0
Payments to noncontrolling interests			(143)
Purchase of noncontrolling interests				(73)
Exercises of Put Right				0
Other			(41)	(4)
Redeemable Noncontrolling Interest
Noncontrolling Interests
Other comprehensive income (loss)			(55)	161
Payments of noncontrolling interests				0
Payments to noncontrolling interests			0
Exercises of Put Right				(53)
Other			0	0
Redeemable Noncontrolling Interests
Beginning balance			1,459	1,327
Net income attributable to noncontrolling interests			34	32
Other comprehensive income (loss)			(55)	161
Reclassification of recurring compensation to other accrued liabilities			(34)	(32)
Payments to noncontrolling interests			0
Purchase of noncontrolling interests				0
Exercises of Put Right				(53)
Other			0	0
Ending balance	$ 1,404	$ 1,435	$ 1,404	$ 1,435