Equity Method Investments - Summarized Financial Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Balance Sheet Information
Current Assets	$ 681	$ 387
Noncurrent Assets	5,306	575
Current Liabilities	607	198
Noncurrent Liabilities	2,243	81
Statements of Operations Information
Operating Revenues	1,018	855	$ 790
Operating Expenses	853	284	303
Operating Income	165	571	487
Other (Loss) Income, net	(33)	3	15
Income Before Income Taxes	132	574	502
Income Tax Provision	72	152	136
Net Income	$ 60	$ 422	$ 366