Redeemable Noncontrolling Interests and Noncontrolling Interests - Schedule of Changes in Redeemable Noncontrolling Interests and Noncontrolling Interests (Details) - USD ($) $ in Millions	3 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Noncontrolling Interest [Line Items]
Beginning balance	$ 178
Net income attributable to noncontrolling interests	56	$ 18
Other comprehensive income (loss)	116
Ending balance	210
Redeemable Noncontrolling Interests
Beginning balance	1,327
Other comprehensive income (loss)	116
Ending balance	1,390
Noncontrolling Interest
Noncontrolling Interest [Line Items]
Beginning balance	178	84
Net income attributable to noncontrolling interests	47	7
Other comprehensive income (loss)	0	0
Payments to noncontrolling interests	(18)
Purchase of noncontrolling interests		152
Other	3	(1)
Ending balance	210	242
Redeemable Noncontrolling Interests
Other comprehensive income (loss)	0	0
Payments to noncontrolling interests	(18)
Exercise of Put Right	0
Purchase of noncontrolling interests		152
Other	3	(1)
Redeemable Noncontrolling Interest
Noncontrolling Interest [Line Items]
Other comprehensive income (loss)	116	(66)
Payments to noncontrolling interests	0
Purchase of noncontrolling interests		0
Other	0	0
Redeemable Noncontrolling Interests
Beginning balance	1,327	1,406
Net income attributable to noncontrolling interests	9	11
Other comprehensive income (loss)	116	(66)
Reclassification of recurring compensation to other accrued liabilities	(9)	(11)
Payments to noncontrolling interests	0
Exercise of Put Right	(53)
Purchase of noncontrolling interests		0
Other	0	0
Ending balance	$ 1,390	$ 1,340