Redeemable Noncontrolling Interest - USD ($) $ in Millions	3 Months Ended
	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2018	Mar. 31, 2018
Temporary Equity [Abstract]
Beginning balance	$ 1,004	$ 1,004	$ 1,000	$ 1,000
Net income attributable to redeemable noncontrolling interest	21	20	20	16
Distributions to noncontrolling interests	(20)	(20)	(17)	(16)
Ending balance	$ 1,005	$ 1,004	$ 1,003	$ 1,000