Long-term Debt - Debt Table (Details) - USD ($) $ in Millions | Jun. 14, 2019 | Apr. 29, 2019 | Jun. 30, 2019 | Jun. 20, 2019 | May 01, 2019 | Dec. 31, 2018 | May 31, 2018 |
Debt Instrument [Line Items] | | | | | | | |
Long-term debt — affiliate | | | $ 0 | | | $ 44 | |
Long-term debt | | | 6,183 | | | 6,038 | |
Current portion of long-term debt — external | | | (1,914) | | | (529) | |
Deferred finance costs, net | | | (77) | | | (61) | |
Long-term debt, excluding current maturities | | | 4,192 | | | 5,448 | |
Long-term debt - affiliate, due 2019 | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Long-term debt — affiliate | | | $ 0 | | | 215 | |
Debt instrument, interest rate, stated percentage | | | 3.58% | | | | |
Intercompany Credit Agreement due 2020 | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Long-term debt — affiliate | | | $ 44 | | | 44 | |
Debt instrument, interest rate, stated percentage | | | 3.325% | | | | |
5.375% Senior Notes due in 2024 | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Senior notes | | | $ 500 | | | 500 | |
Debt instrument, interest rate, stated percentage | | | 5.375% | | | | |
5.75% Senior Notes due 2025 | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Senior notes | | | $ 600 | | | 600 | |
Debt instrument, interest rate, stated percentage | | | 5.75% | | | | |
5.00% Senior Notes due in 2026 | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Senior notes | | | $ 350 | | | 350 | |
Debt instrument, interest rate, stated percentage | | | 5.00% | | | | |
Revolving Credit Facility | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Long-term debt | | | $ 0 | | | 0 | |
Debt instrument, basis spread on variable rate | | | 1.75% | | | | |
Debt instrument, description of variable rate basis | | | 3-Month LIBOR | | | | |
Agua Caliente Borrower 2 | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Long-term debt | | | $ 38 | | | 39 | |
Debt instrument, interest rate, stated percentage | | | 5.43% | | | | |
Alpine Financing Agreement, due 2022 | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Long-term debt | | | $ 125 | | | 127 | |
Debt instrument, basis spread on variable rate | | | 1.75% | | | | |
Debt instrument, description of variable rate basis | | | 3-Month LIBOR | | | | |
Alta Wind I-V, lease financing arrangement, due 2034 and 2035 | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Long-term debt | | | $ 859 | | | 886 | |
Buckthorn Solar, due 2025 | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Long-term debt | | | $ 131 | | | 132 | $ 132 |
Debt instrument, basis spread on variable rate | | | 1.75% | | | | |
Debt instrument, description of variable rate basis | | | 1-Month LIBOR | | | | |
CVSR Financing Agreement | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Long-term debt | | | $ 704 | | | 720 | |
CVSR Holdco due 2037 | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Long-term debt | | | $ 182 | | | 188 | |
Debt instrument, interest rate, stated percentage | | | 4.68% | | | | |
Duquesne Due 2059 | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Long-term debt | | | $ 95 | | | 0 | |
Debt instrument, interest rate, stated percentage | | | 4.62% | | | | |
El Segundo Energy Center, due 2023 | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Long-term debt | | | $ 320 | | | 352 | |
Debt instrument, description of variable rate basis | | | 3-Month LIBOR | | | | |
Energy Center Minneapolis Series C Notes | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Long-term debt | | | $ 328 | | | 328 | |
Laredo Ridge Wind, LLC, due in 2026 | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Long-term debt | | | $ 86 | | | 89 | |
Debt instrument, basis spread on variable rate | | | 2.125% | | | | |
Debt instrument, description of variable rate basis | | | 3-Month LIBOR | | | | |
Kansas South, due in 2030 | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Long-term debt | | | $ 25 | | | 26 | |
Debt instrument, basis spread on variable rate | | | 2.00% | | | | |
Debt instrument, description of variable rate basis | | | 3-Month LIBOR | | | | |
Kawailoa Solar Holdings LLC, due 2026 | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Long-term debt | | | $ 128 | | | 0 | |
Debt instrument, basis spread on variable rate | | | 1.375% | | | | |
Debt instrument, description of variable rate basis | | | 3-Month LIBOR | | | | |
Marsh Landing Term Loan Facility | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Long-term debt | | | $ 249 | | | 263 | |
Debt instrument, basis spread on variable rate | | | 2.125% | | | | |
Debt instrument, description of variable rate basis | | | 3-Month LIBOR | | | | |
Oahu Solar Holdings LLC, due 2026 | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Long-term debt | | | $ 150 | | | 0 | |
Debt instrument, basis spread on variable rate | | | 1.375% | | | | |
Debt instrument, description of variable rate basis | | | 3-Month LIBOR | | | | |
Repowering Partnership Holdco LLC, due 2020 | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Long-term debt | | | $ 219 | | | 0 | |
Debt instrument, basis spread on variable rate | | | 0.85% | | | | |
South Trent Wind Due 2028 | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Long-term debt | | | $ 44 | | | 50 | |
Debt instrument, basis spread on variable rate | | | 1.35% | | | | |
Debt instrument, description of variable rate basis | | | 3-Month LIBOR | | | | |
Tapestry Wind LLC due in 2031 | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Long-term debt | | | $ 161 | | | 151 | |
Debt instrument, basis spread on variable rate | | | 1.375% | | | | |
Debt instrument, description of variable rate basis | | | 3-Month LIBOR | | | | |
Utah Solar Portfolio, due 2022 | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Long-term debt | | | $ 260 | | | 267 | |
Debt instrument, basis spread on variable rate | | | 2.625% | | | | |
Debt instrument, description of variable rate basis | | | 3-Month LIBOR | | | | |
Viento Funding II, Inc., due in 2023 | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Long-term debt | | | $ 42 | | | 146 | |
Debt instrument, basis spread on variable rate | | | 2.00% | | | | |
Debt instrument, description of variable rate basis | | | 3-Month LIBOR | | | | |
Walnut Creek Energy, LLC, due in 2023 | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Long-term debt | | | $ 209 | | | 222 | |
Debt instrument, basis spread on variable rate | | | 1.75% | | | | |
Debt instrument, description of variable rate basis | | | 3-Month LIBOR | | | | |
Other Debt | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Long-term debt | | | $ 334 | | | 343 | |
Project Level Debt | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Long-term debt | | | $ 4,689 | | | $ 4,329 | |
El Segundo Energy Center, due 2023 Tranche B | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Debt instrument, basis spread on variable rate | | | 2.375% | | | | |
El Segundo Energy Center, due 2023 Tranche A | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Debt instrument, basis spread on variable rate | | | 1.75% | | | | |
Letter of Credit | Revolving Credit Facility | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Letters of credit outstanding, amount | | | $ 45 | | | | |
Letter of Credit | Agua Caliente Borrower 2 | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Letters of credit outstanding, amount | | | 17 | | | | |
Letter of Credit | Alpine Financing Agreement, due 2022 | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Letters of credit outstanding, amount | | | 16 | | | | |
Letter of Credit | Alta Wind I-V, lease financing arrangement, due 2034 and 2035 | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Letters of credit outstanding, amount | | | 29 | | | | |
Letter of Credit | Buckthorn Solar, due 2025 | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Letters of credit outstanding, amount | | | 26 | | | | |
Letter of Credit | CVSR Financing Agreement | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Letters of credit outstanding, amount | | | 0 | | | | |
Letter of Credit | CVSR Holdco due 2037 | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Letters of credit outstanding, amount | | | 13 | | | | |
Letter of Credit | Duquesne Due 2059 | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Debt instrument, interest rate, stated percentage | | | | | 4.62% | | |
Letter of Credit | El Segundo Energy Center, due 2023 | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Letters of credit outstanding, amount | | | 138 | | | | |
Letter of Credit | Energy Center Minneapolis Series C Notes | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Letters of credit outstanding, amount | | | 0 | | | | |
Letter of Credit | Laredo Ridge Wind, LLC, due in 2026 | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Letters of credit outstanding, amount | | | 10 | | | | |
Letter of Credit | Kansas South, due in 2030 | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Letters of credit outstanding, amount | | | 2 | | | | |
Letter of Credit | Kawailoa Solar Holdings LLC, due 2026 | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Letters of credit outstanding, amount | | | 4 | | | | |
Letter of Credit | Marsh Landing Term Loan Facility | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Letters of credit outstanding, amount | | | 46 | | | | |
Letter of Credit | Oahu Solar Holdings LLC, due 2026 | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Letters of credit outstanding, amount | | | 10 | | | | |
Letter of Credit | South Trent Wind Due 2028 | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Letters of credit outstanding, amount | | | 12 | | | | |
Letter of Credit | Tapestry Wind LLC due in 2031 | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Letters of credit outstanding, amount | | | 24 | $ 6 | | | |
Letter of Credit | Utah Solar Portfolio, due 2022 | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Letters of credit outstanding, amount | | | 13 | | | | |
Letter of Credit | Viento Funding II, Inc., due in 2023 | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Letters of credit outstanding, amount | | | 14 | | | | |
Letter of Credit | Walnut Creek Energy, LLC, due in 2023 | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Letters of credit outstanding, amount | | | 93 | | | | |
Letter of Credit | Other Debt | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Letters of credit outstanding, amount | | | $ 24 | | | | |
Minimum | Alta Wind I-V, lease financing arrangement, due 2034 and 2035 | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Debt instrument, interest rate, stated percentage | | | 5.696% | | | | |
Minimum | CVSR Financing Agreement | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Debt instrument, interest rate, stated percentage | | | 2.339% | | | | |
Maximum | Alta Wind I-V, lease financing arrangement, due 2034 and 2035 | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Debt instrument, interest rate, stated percentage | | | 7.015% | | | | |
Maximum | CVSR Financing Agreement | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Debt instrument, interest rate, stated percentage | | | 3.775% | | | | |
London Interbank Offered Rate (LIBOR) | Kansas South, due in 2030 | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Debt instrument, basis spread on variable rate | | | 2.00% | | | | |
London Interbank Offered Rate (LIBOR) | Utah Solar Portfolio, due 2022 | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Debt instrument, basis spread on variable rate | | | 2.625% | | | | |
London Interbank Offered Rate (LIBOR) | Letter of Credit | South Trent Wind Due 2028 | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Debt instrument, basis spread on variable rate | 1.35% | | | | | | |
London Interbank Offered Rate (LIBOR) | Letter of Credit | Tapestry Wind LLC due in 2031 | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Debt instrument, basis spread on variable rate | | 1.375% | | | | | |