Investments Accounted for by the Equity Method and Variable Interest Entities - Narrative (Details) $ in Millions													1 Months Ended			2 Months Ended	6 Months Ended	12 Months Ended
	Dec. 21, 2020 USD ($) MW	Nov. 20, 2020 USD ($) MW	Nov. 02, 2020 USD ($) fund project MW	May 11, 2020 USD ($)	Feb. 07, 2020 USD ($)	Dec. 22, 2019 USD ($)	Nov. 26, 2019 USD ($)	Nov. 12, 2019 USD ($)	Jan. 02, 2019 USD ($)	Aug. 31, 2018 USD ($) MW	Mar. 31, 2018 USD ($)	Jun. 30, 2015 USD ($)	Jan. 31, 2021 USD ($)	Jan. 31, 2021 USD ($)	May 31, 2018 USD ($)	Mar. 31, 2020 USD ($)	Jun. 30, 2020 USD ($)	Dec. 31, 2020 USD ($) MW	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	May 29, 2020 USD ($)	May 28, 2020 USD ($)	Dec. 27, 2019 USD ($)	Jun. 14, 2019 USD ($)	May 07, 2019 USD ($)	Mar. 08, 2019 USD ($)	Aug. 30, 2018	Mar. 30, 2018 MW
Schedule of Equity Method Investments [Line Items]
Retained earnings, undistributed earnings from equity method investees																		$ 10	$ 138
Payments to acquire equity method investments																		11	13	$ 34
Non-recourse debt																		481
Equity investments in affiliates																		741	1,183
Ownership interest acquired																												100.00%
Non-controlling interest		$ 119
Noncontrolling interest																		$ 890	413
Percentage of cash available for distributions																		95.00%
Net contributions from noncontrolling interests																		$ 247	174	91
Taxable income allocation, pre-flip					99.00%
Long-term debt																		7,043	6,858
Removed related noncontrolling interest balance				$ 8															19	52
Depreciation																		$ 420	395	$ 330
Yield Protection Agreement
Schedule of Equity Method Investments [Line Items]
Cash distribution reallocation percentage																		80.00%
Number of years after date of arrangement that reallocation of cash contributions begins																		15 years
Estimated liability under arrangement																		$ 15
DGPV Holdco 3
Schedule of Equity Method Investments [Line Items]
Power generation capacity, megawatts | MW			286															113
Remaining lease term																		21 years
Income allocation percentage																					99.00%
Equity investments in affiliates																						$ (155)
Investment in consolidated entity																	$ 10
Number of tax equity funds | fund			7
Number of solar projects | project			172
Long-term debt																					$ 206
Removed related noncontrolling interest balance																		$ 20
DGPV Holdco 1 and 2
Schedule of Equity Method Investments [Line Items]
Adjustment to noncontrolling interest			$ 144
Long-term debt			$ 160
Lighthouse Renewable Holdco LLC
Schedule of Equity Method Investments [Line Items]
Income allocation percentage																		50.01%
Rosie TargetCo LLC
Schedule of Equity Method Investments [Line Items]
Income allocation percentage	50.00%
Repowering Partnership II LLC
Schedule of Equity Method Investments [Line Items]
Cash consideration to acquire interest joint venture				$ 70
Depreciation																			$ 54
Utah Solar Portfolio
Schedule of Equity Method Investments [Line Items]
Business acquisition, consideration transferred, working capital																		$ 106
Equity investments in affiliates																		$ 255
Percentage of cash available for distributions																		50.00%
Equity method investment, ownership percentage																		50.00%
Desert Sunlight
Schedule of Equity Method Investments [Line Items]
Payments to acquire equity method investments												$ 285
Business acquisition, consideration transferred, working capital												$ 171
Equity investments in affiliates																		$ 244
Equity method investment, ownership percentage																		25.00%
Agua Caliente Solar
Schedule of Equity Method Investments [Line Items]
Equity investments in affiliates																		$ 83
Equity method investment, ownership percentage																		16.00%
Elkhorn Ridge
Schedule of Equity Method Investments [Line Items]
Equity investments in affiliates																		$ 38
Equity method investment, ownership percentage																		66.70%
San Juan Mesa
Schedule of Equity Method Investments [Line Items]
Equity investments in affiliates																		$ 33
Equity method investment, ownership percentage																		75.00%
Avenal
Schedule of Equity Method Investments [Line Items]
Equity investments in affiliates																		$ (2)
Equity method investment, ownership percentage																		50.00%
Kawailoa Solar Holdings LLC
Schedule of Equity Method Investments [Line Items]
Non-controlling interest						$ 61																	$ 7
Oahu Solar, Lanikuhana
Schedule of Equity Method Investments [Line Items]
Power generation capacity, megawatts | MW										15
Power purchase agreement period										22 years
Oahu Solar, Waipio
Schedule of Equity Method Investments [Line Items]
Power generation capacity, megawatts | MW										46
Repowering Partnership LLC
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage																											21.00%
Depreciation																		$ 9
Elbow TE Holdco
Schedule of Equity Method Investments [Line Items]
Cash considerations							$ 4
Wildorado TE Holdco
Schedule of Equity Method Investments [Line Items]
Income allocation percentage					5.00%
Cash considerations																$ 112
Kawailoa Partnership
Schedule of Equity Method Investments [Line Items]
Power generation capacity, megawatts | MW										49
Payments to acquire businesses, gross										$ 9
Power purchase agreement period										22 years
Capital contribution, percent																									20.00%
Non-controlling interest																									$ 2
Outstanding debt at time of acquisition																									120
Noncontrolling interest																									$ 21
Buckthorn Solar Drop Down Asset
Schedule of Equity Method Investments [Line Items]
Power generation capacity, megawatts | MW																												154
Cash considerations											$ 42
Non-controlling interest											$ 19
Zephyr Oahu Partnership LLC
Schedule of Equity Method Investments [Line Items]
Capital contribution, percent																										20.00%
Non-controlling interest																										$ 4
Outstanding debt at time of acquisition																										143
Zephyr Oahu Partnership LLC | Oahu Solar Partnership
Schedule of Equity Method Investments [Line Items]
Payments to acquire businesses, gross										$ 20
Rosie TargetCo LLC
Schedule of Equity Method Investments [Line Items]
Power generation capacity, megawatts | MW	192
Ownership interest acquired	100.00%
Payments to acquire businesses, gross	$ 23
Non-controlling interest	52
Outstanding debt at time of acquisition	$ 205
Langford Holding LLC
Schedule of Equity Method Investments [Line Items]
Power generation capacity, megawatts | MW		160
Ownership interest acquired		100.00%
Payments to acquire businesses, gross		$ 64
Financial Institutions | November 2015 Drop Down Assets
Schedule of Equity Method Investments [Line Items]
Ownership interest acquired									100.00%
Cash considerations									$ 19
Taxable income allocation, pre-flip																		99.00%
Wind TE Holdco | Repowering Partnership II LLC
Schedule of Equity Method Investments [Line Items]
Income allocation percentage							59.63%
CWSP Wildorado Elbow Holding LLC | Repowering Partnership II LLC
Schedule of Equity Method Investments [Line Items]
Income allocation percentage							40.37%
Buckthorn Solar Drop Down Asset
Schedule of Equity Method Investments [Line Items]
Power purchase agreement period															25 years
Net contributions from noncontrolling interests															$ 80
Alta X and XI TE Holdco | Financial Institutions
Schedule of Equity Method Investments [Line Items]
Taxable income allocation, pre-flip																		99.00%
Taxable income allocation, post-flip																		5.00%
NRG
Schedule of Equity Method Investments [Line Items]
Ownership interest acquired											100.00%
Buckthorn Renewables, LLC | Buckthorn Solar Portfolio, LLC
Schedule of Equity Method Investments [Line Items]
Percentage of ownership											100.00%
Repowering Partnership II LLC | CWSP Wildorado Elbow Holding LLC
Schedule of Equity Method Investments [Line Items]
Income allocation percentage																		39.86%
Repowering Partnership II LLC | Wind TE Holdco LLC
Schedule of Equity Method Investments [Line Items]
Income allocation percentage																		60.14%
Langford Wind Project
Schedule of Equity Method Investments [Line Items]
Power generation capacity, megawatts | MW		160
Tax Equity Investors | Oahu Solar Partnership
Schedule of Equity Method Investments [Line Items]
Net contributions from noncontrolling interests								$ 71
Tax Equity Investors | Zephyr Oahu Partnership LLC
Schedule of Equity Method Investments [Line Items]
Noncontrolling interest																										$ 18
CEG | Rosie TargetCo LLC
Schedule of Equity Method Investments [Line Items]
Ownership interest acquired	100.00%
CEG | Langford Holding LLC
Schedule of Equity Method Investments [Line Items]
Ownership interest acquired		100.00%
Cash considerations		$ 55
Third Party Investor | Langford Holding LLC
Schedule of Equity Method Investments [Line Items]
Ownership interest acquired		100.00%
Cash considerations		$ 9
Second Year through Flip Point | Alta X and XI TE Holdco
Schedule of Equity Method Investments [Line Items]
Percentage of cash available for distributions																		94.34%
Post-Flip Point | Alta X and XI TE Holdco
Schedule of Equity Method Investments [Line Items]
Percentage of cash available for distributions																		97.12%
Post-Flip Point | Spring Canyon
Schedule of Equity Method Investments [Line Items]
Percentage of cash available for distributions																		95.00%
Post-Flip Point | Spring Canyon | Financial Institutions
Schedule of Equity Method Investments [Line Items]
Percentage of cash available for distributions																		5.00%
Pre-determined Date Through Flip Point If Flip Has Not Occured | Alta X and XI TE Holdco | Financial Institutions
Schedule of Equity Method Investments [Line Items]
Percentage of cash available for distributions																		100.00%
Pre-Flip Point | Spring Canyon
Schedule of Equity Method Investments [Line Items]
Percentage of cash available for distributions																		65.19%
Pre-Flip Point | Spring Canyon | Financial Institutions
Schedule of Equity Method Investments [Line Items]
Percentage of cash available for distributions																		34.81%
Wind Farms | Spring Canyon II
Schedule of Equity Method Investments [Line Items]
Power generation capacity, megawatts | MW																		32
Ownership interest acquired																		90.10%
Wind Farms | Spring Canyon III
Schedule of Equity Method Investments [Line Items]
Power generation capacity, megawatts | MW																		28
Capital Unit, Class A | Utah Solar Portfolio
Schedule of Equity Method Investments [Line Items]
Percentage of ownership											100.00%
Capital Unit, Class B | Financial Institutions | Utah Solar Portfolio
Schedule of Equity Method Investments [Line Items]
Taxable income allocation, pre-flip																		99.00%
Taxable income allocation, post-flip																		50.00%
Capital Unit, Class B | Buckthorn Solar Portfolio, LLC | Buckthorn Holdings, LLC
Schedule of Equity Method Investments [Line Items]
Percentage of ownership											100.00%
Kawailoa Partnership | Kawailoa Solar Project
Schedule of Equity Method Investments [Line Items]
Ownership interest																		51.00%
Third Party Investor | Kawailoa Solar Project
Schedule of Equity Method Investments [Line Items]
Ownership interest																		49.00%
Third Party Investor | Capital Unit, Class A | Elbow TE Holdco
Schedule of Equity Method Investments [Line Items]
Ownership interest acquired							100.00%
Membership interest							$ 89
Third Party Investor | Capital Unit, Class A | Wildorado TE Holdco
Schedule of Equity Method Investments [Line Items]
Ownership interest acquired					100.00%
Membership interest					$ 148
Wind Global LLC | Wind Farms
Schedule of Equity Method Investments [Line Items]
Noncontrolling interest, ownership percentage by noncontrolling owners																		9.90%
Rosie Class B LLC | Rosie TargetCo LLC
Schedule of Equity Method Investments [Line Items]
Percentage of ownership	100.00%
Rosie TE Holdco LLC | Rosie Class B LLC
Schedule of Equity Method Investments [Line Items]
Percentage of ownership	100.00%
Langford Tax Equity Partnership LLC | Langford Class B Holdco LLC
Schedule of Equity Method Investments [Line Items]
Ownership interest		100.00%
Langford Class B Holdco LLC | Langford Holding LLC
Schedule of Equity Method Investments [Line Items]
Ownership interest		100.00%
Langford Wind Project | Langford Tax Equity Partnership LLC
Schedule of Equity Method Investments [Line Items]
Ownership interest		100.00%
ITC Bridge Loan | Kawailoa Solar Holdings LLC
Schedule of Equity Method Investments [Line Items]
Repayments of debt						57
ITC Bridge Loan | Oahu Solar Partnership
Schedule of Equity Method Investments [Line Items]
Repayments of debt								$ 67
Term Debt | Kawailoa Solar Holdings LLC
Schedule of Equity Method Investments [Line Items]
Proceeds from debt						$ 5
Construction Loan
Schedule of Equity Method Investments [Line Items]
Long-term debt							93
Repowering Partnership Holdco LLC, due 2020
Schedule of Equity Method Investments [Line Items]
Repayments of debt					$ 260		$ 93
Outstanding debt at time of acquisition																								$ 352
Repowering Partnership Holdco LLC, due 2020 | Variable Interest Entity, Primary Beneficiary
Schedule of Equity Method Investments [Line Items]
Debt instrument, face amount																		$ 352
Affiliated Entity
Schedule of Equity Method Investments [Line Items]
Percentage of cash available for distributions																		5.00%
Affiliated Entity | Clearway Renew LLC | Oahu Solar Partnership
Schedule of Equity Method Investments [Line Items]
Noncontrolling interest																		$ 16
Percentage of ownership																		80.00%
Subsequent Event | Rosie TargetCo LLC
Schedule of Equity Method Investments [Line Items]
Payments to acquire businesses, gross													$ 1	$ 24