Variable Interest Entities - Schedule of Variable Interest Entities (Details) - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018	Sep. 30, 2018
Current assets:
Cash and cash equivalents	$ 106	$ 101
Restricted cash	0	4
Trade receivables	65	50
Prepaid expenses	16	18
Other current assets	22	15
Total current assets	241	211
Restricted cash	13	18
Construction in progress	500	259
Property, plant and equipment, net	3,917	4,119	$ 4,110
Unconsolidated investments	281	270	372
Deferred financing costs, net	7	8
Intangible assets, net	211	219
Other assets	101	34
Total assets	5,396	5,294	$ 5,372
Current liabilities:
Accounts payable and other accrued liabilities	66	67
Accrued construction costs	51	27
Current portion of long-term debt, net	329	56
Other current liabilities	27	11
Total current liabilities	717	478
Long-term debt, net	2,172	2,004
Intangible liability, net	45	56
Asset retirement obligations	213	185
Other long-term liabilities	128	71
Deferred revenue	26	26
Total liabilities	3,567	3,135
Variable Interest Entity, Primary Beneficiary
Current assets:
Cash and cash equivalents	32	36
Restricted cash	0	4
Trade receivables	19	13
Prepaid expenses	3	6
Other current assets	4	2
Total current assets	58	61
Restricted cash	2	3
Construction in progress	0	1
Property, plant and equipment, net	2,083	2,156
Unconsolidated investments	54	0
Deferred financing costs, net	1	2
Intangible assets, net	11	12
Other assets	18	12
Total assets	2,227	2,247
Current liabilities:
Accounts payable and other accrued liabilities	26	27
Accrued construction costs	0	1
Current portion of long-term debt, net	5	4
Other current liabilities	5	5
Total current liabilities	36	37
Long-term debt, net	150	149
Intangible liability, net	45	48
Asset retirement obligations	59	57
Other long-term liabilities	42	36
Deferred revenue	26	26
Total liabilities	$ 358	$ 353