Redeemable Noncontrolling Interests and Noncontrolling Interests - Schedule of Changes in Noncontrolling Interests and Redeemable Noncontrolling Interest (Details) - USD ($) $ in Millions	12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2018
Stockholders' Equity Attributable to Noncontrolling Interest [Roll Forward]
Beginning balance	$ 193
Net income attributable to noncontrolling interests	220	$ 221	$ 230
Other comprehensive income	(3)	66
Ending balance	217	193
Redeemable Noncontrolling Interest, Beginning balance	1,393
Payments to noncontrolling interests	(154)	(184)	(98)
Redeemable Noncontrolling Interest, Ending balance	1,402	1,393
Noncontrolling interests
Stockholders' Equity Attributable to Noncontrolling Interest [Roll Forward]
Beginning balance	193	253
Net income attributable to noncontrolling interests	178	176
Other comprehensive income	0	0
Other	0	(52)
Ending balance	217	193	253
Payments to noncontrolling interests	(154)	(184)	(98)
Other	0	(52)
Redeemable Noncontrolling Interests
Stockholders' Equity Attributable to Noncontrolling Interest [Roll Forward]
Other comprehensive income	3	(66)
Other	6	0
Redeemable Noncontrolling Interest, Beginning balance	1,393	1,459
Net income attributable to noncontrolling interests	42	45
Reclassification of recurring compensation to other accrued liabilities	(42)	(45)
Payments to noncontrolling interests	0	0
Other	6	0
Redeemable Noncontrolling Interest, Ending balance	$ 1,402	$ 1,393	$ 1,459