Leases (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Jan. 01, 2018	[2]	Dec. 31, 2015
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Increase to noncontrolling interests	[1]				$ 1,423		$ 8	[3]
ROU assets		$ 24	$ 30
Operating lease liabilities		$ 24	$ 30
Weighted average discount rate		4.46%
Weighted-average remaining lease term		25 years	27 years
Operating lease costs		$ 2	$ 2	$ 2
Variable lease costs		5	$ 5	$ 3
Fixed payments due next twelve months		2
Fixed payments due 2020		2
Fixed payments due 2021		2
Fixed payments due 2022		2
Fixed payments due 2023		2
Fixed payments due thereafter		$ 28
Minimum [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Lease extension term		10 years
Maximum [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Lease extension term		20 years
Noncontrolling Interest [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Increase to noncontrolling interests	[1]				$ 1,416		8	[3]
Accounting Standards Update 2016-02 [Member] | Noncontrolling Interest [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Increase to noncontrolling interests	[1],[3]						$ 8

[1] Prior-period financial information has been retrospectively adjusted as discussed in Note 14.

[2] See Note 2 - Differential Membership Interests.

[3] See Note 14.