Debt & Non-recourse Debt - Schedule of Contractual Maturities of Debt (Details) - USD ($) $ in Millions		Sep. 30, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
2019 (remaining)		$ 3
2020		12
2021		11
2022		10
2023		463
Thereafter		323
Long-term debt	[1]	822	$ 612
Non-recourse Debt
Debt Instrument [Line Items]
2019 (remaining)		51
2020		247
2021		155
2022		110
2023		108
Thereafter		133
Long-term debt	[2]	804	$ 766
Debt and Non-recourse Debt
Debt Instrument [Line Items]
2019 (remaining)		54
2020		259
2021		166
2022		120
2023		571
Thereafter		456
Long-term debt		$ 1,626

[1] As of September 30, 2019 and December 31, 2018, weighted-average interest rates were 4.739 percent and 5.170 percent, respectively.

[2] As of September 30, 2019 and year ended December 31, 2018, weighted-average interest rates were 2.874 percent and 3.126 percent, respectively.