Investments Accounted for by the Equity Method and Variable Interest Entities - Additional Information (Details) $ in Millions				12 Months Ended
	May 31, 2018 USD ($)	Mar. 31, 2018 USD ($)	Jun. 30, 2015 USD ($)	Dec. 31, 2018 USD ($) generatingunit MW	Dec. 31, 2017 USD ($)		Dec. 31, 2016 USD ($)		Aug. 31, 2018 USD ($)	Mar. 30, 2018 MW	Oct. 12, 2017 USD ($)	Mar. 27, 2017 USD ($) MW
Schedule of Equity Method Investments [Line Items]
Net contributions from noncontrolling interests				$ 91	$ 13	[1]	$ 5	[1]
Less: Net income (loss) attributable to noncontrolling interests				2	(15)	[2]	$ (51)	[2]
Retained earnings, undistributed earnings from equity method investees				87	57
Non-recourse debt				878
Ownership interest acquired										100.00%
Equity investments in affiliates				1,172	1,178	[3]
GCE Holding LLC
Schedule of Equity Method Investments [Line Items]
Equity investments in affiliates				$ 98
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				$ 264
Equity method investment, ownership percentage				25.00%
Utah Portfolio
Schedule of Equity Method Investments [Line Items]
Business acquisition, consideration transferred, working capital				$ 106
Non-recourse debt												$ 287
Percentage of cash available for distributions				50.00%
Equity investments in affiliates				$ 317
Equity method investment, ownership percentage				50.00%
PG&E
Schedule of Equity Method Investments [Line Items]
Pro-rate share of debt held by unconsolidated affiliates				$ 432
DGPV Holdco 1
Schedule of Equity Method Investments [Line Items]
Power generation gapacity, megawatts | MW				52
Equity investments in affiliates				$ 81
Equity method investment, ownership percentage				95.00%
NRG DGPV Holdco 2
Schedule of Equity Method Investments [Line Items]
Remaining lease term				20 years
Equity investments in affiliates				$ 63
Equity method investment, ownership percentage				95.00%
DGPV Holdco 3
Schedule of Equity Method Investments [Line Items]
Power generation gapacity, megawatts | MW				59
Remaining lease term				21 years
Due to related parties				$ 9
Equity investments in affiliates				$ 116
Equity method investment, ownership percentage				99.00%
NRG DGPV Holdco
Schedule of Equity Method Investments [Line Items]
Equity investments in affiliates				$ 260
RPV Holdco
Schedule of Equity Method Investments [Line Items]
Equity investments in affiliates				$ 29
Equity method investment, ownership percentage				95.00%
Agua Caliente Borrower 2
Schedule of Equity Method Investments [Line Items]
Power generation gapacity, megawatts | MW												46
Non-recourse debt												$ 41
Equity investments in affiliates				$ 90
Equity method investment, ownership percentage				16.00%
Elkhorn Ridge Wind, LLC
Schedule of Equity Method Investments [Line Items]
Equity investments in affiliates				$ 59
Equity method investment, ownership percentage				66.70%
San Juan Mesa Wind Project, LLC
Schedule of Equity Method Investments [Line Items]
Equity investments in affiliates				$ 57
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%
Buckthorn Solar Drop Down Asset
Schedule of Equity Method Investments [Line Items]
Power generation gapacity, megawatts | MW										154
Less: noncontrolling interest		$ 19
Less: Net income (loss) attributable to noncontrolling interests					$ 0
Taxable income allocation, pre-flip				67.00%
Cash considerations		$ 42
Taxable income allocation, post-flip				99.00%
Financial Institutions | November 2015 Drop Down Assets
Schedule of Equity Method Investments [Line Items]
Taxable income allocation, pre-flip				99.00%
Ownership interest acquired				100.00%
Cash considerations				$ 19
Buckthorn Solar Drop Down Asset
Schedule of Equity Method Investments [Line Items]
Net contributions from noncontrolling interests	$ 80
Less: Net income (loss) attributable to noncontrolling interests				$ (55)
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%
Spring Canyon
Schedule of Equity Method Investments [Line Items]
Noncontrolling interest, ownership percentage by noncontrolling owners				9.90%
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
Schedule of Equity Method Investments [Line Items]
Ownership interest acquired				90.10%
Wind Farms | Spring Canyon II
Schedule of Equity Method Investments [Line Items]
Power generation gapacity, megawatts | MW				32
Wind Farms | Spring Canyon III
Schedule of Equity Method Investments [Line Items]
Power generation gapacity, megawatts | MW				28
Capital Unit, Class A | Utah Portfolio
Schedule of Equity Method Investments [Line Items]
Percentage of ownership				100.00%
Capital Unit, Class B | Financial Institutions | Utah Portfolio
Schedule of Equity Method Investments [Line Items]
Taxable income allocation, pre-flip				99.00%
Taxable income allocation, post-flip				50.00%
Tax Equity Financed Portfolio of Leases - Commercial PV 1 | DGPV Holdco 1
Schedule of Equity Method Investments [Line Items]
Remaining lease term				17 years
Tax Equity Financed Portfolio of Leases - Commercial PV 1 | NRG DGPV Holdco 2
Schedule of Equity Method Investments [Line Items]
Power generation gapacity, megawatts | MW				113
Tax Equity Financed Portfolio of Leases | RPV Holdco
Schedule of Equity Method Investments [Line Items]
Power generation gapacity, megawatts | MW				30
Number of solar leases in portfolio | generatingunit				5,400
Existing Portfolio of Leases | RPV Holdco
Schedule of Equity Method Investments [Line Items]
Power generation gapacity, megawatts | MW				14
Remaining lease term				14 years
Number of solar leases in portfolio | generatingunit				2,200
Maximum | Tax Equity Financed Portfolio of Leases | DGPV Holdco 1
Schedule of Equity Method Investments [Line Items]
Equity investments in affiliates				$ 100
Maximum | Tax Equity Financed Portfolio of Leases | NRG DGPV Holdco 2
Schedule of Equity Method Investments [Line Items]
Equity investments in affiliates											$ 60
Maximum | Tax Equity Financed Portfolio of Leases | DGPV Holdco 3
Schedule of Equity Method Investments [Line Items]
Equity investments in affiliates				$ 70
Maximum | Tax Equity Financed Portfolio of Leases | RPV Holdco
Schedule of Equity Method Investments [Line Items]
Remaining lease term				17 years
Minimum | Tax Equity Financed Portfolio of Leases | DGPV Holdco 3
Schedule of Equity Method Investments [Line Items]
Equity investments in affiliates				$ 50
Clearway Energy LLC | CEG | Repowering Partnership LLC
Schedule of Equity Method Investments [Line Items]
Business acquisition, consideration transferred, working capital									$ 35
Noncontrolling interest, ownership percentage by noncontrolling owners				21.00%
Wind Global LLC | Wind Farms
Schedule of Equity Method Investments [Line Items]
Noncontrolling interest, ownership percentage by noncontrolling owners				9.90%

[1] Retrospectively adjusted as discussed in Note 1, Nature of Business.

[2] Retrospectively adjusted as discussed in Note 1, Nature of Business.

[3] Retrospectively adjusted as discussed in Note 1, Nature of Business.