Investment in Equity Method Affiliate - Schedule of Investments (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Equity Method Affiliates Reported Amounts:
Equity in earnings (losses) of equity method affiliate, net		$ (222)	$ 5	$ (211)	$ 12
Return on investment in equity method affiliate				14	12
Return of investment in equity method affiliate				9	8
Operating income		100	175	326	507
Net income (loss)		(163)	133	(14)	380
SESH
Equity Method Affiliates Reported Amounts:
Equity in earnings of equity method affiliate		3	5	14	12
Impairment of equity method affiliate investment		(225)	0	(225)	0
Equity in earnings (losses) of equity method affiliate, net		(222)	5	(211)	12
Distributions from equity method affiliate (1)	[1]	4	4	23	20
Return on investment in equity method affiliate				14	12
Return of investment in equity method affiliate				9	8
Revenues		24	27	79	81
Operating income		11	15	40	37
Net income (loss)		$ 6	$ 10	$ 27	$ 24

[1] Distributions from equity method affiliate includes a $14 million and $12 million return on investment and a $9 million and $8 million return of investment for the nine months ended September 30, 2020 and 2019, respectively.