Consolidated Statements of Stockholders' Equity - Unaudited - USD ($) $ in Millions	Total	DGPV Funds	Mesquite Star	Aqua Cliente Acquisition	Rattlensake Down	CEG	Tax Equity Investors	Preferred Stock	Common Stock	Additional Paid-In Capital	Additional Paid-In Capital CEG	Accumulated Deficit	Accumulated Other Comprehensive Loss	Noncontrolling Interest	Noncontrolling Interest DGPV Funds	Noncontrolling Interest Mesquite Star	Noncontrolling Interest Aqua Cliente Acquisition	Noncontrolling Interest Rattlensake Down	Noncontrolling Interest CEG	Noncontrolling Interest Tax Equity Investors
Balance at beginning of period at Dec. 31, 2019	$ 2,263							$ 0	$ 1	$ 1,936		$ (72)	$ (15)	$ 413
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(107)											(29)		(78)
Unrealized gain on derivatives, net of tax	(12)												(6)	(6)
Contributions from CEG, cash						$ 4	$ 150												$ 4	$ 150
Distributions from noncontrolling interests, net of contribution, cash							(2)													(2)
Net proceeds from the issuance of common stock under the ATM Program	10									10
Dividends to common stockholders and distributions to CEG						(42)					$ (24)								(18)
Balance at end of period at Mar. 31, 2020	2,264							0	1	1,922		(101)	(21)	463
Balance at beginning of period at Dec. 31, 2019	2,263							0	1	1,936		(72)	(15)	413
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	11
Balance at end of period at Sep. 30, 2020	2,237							0	1	1,918		(22)	(15)	355
Balance at beginning of period at Mar. 31, 2020	2,264							0	1	1,922		(101)	(21)	463
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	76											47		29
Unrealized gain on derivatives, net of tax	4												2	2
Contributions from, Distributions to CEG, non-cash						8													8
Contributions from CEG, cash	2													2
Distributions from noncontrolling interests, net of contribution, cash	(3)													(3)
Stock-based compensation	1									1
Noncontrolling interest, decrease from redemptions or purchase of interests	(70)	$ (43)												(70)	$ (43)
Non-cash adjustments for change in tax basis	7									7
Net proceeds from the issuance of common stock under the ATM Program	28									28
Dividends to common stockholders and distributions to CEG						(42)					(24)								(18)
Balance at end of period at Jun. 30, 2020	2,232							0	1	1,934		(54)	(19)	370
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	42											32		10
Unrealized gain on derivatives, net of tax	8												4	4
Contributions from, Distributions to CEG, non-cash						(1)													(1)
Distributions from noncontrolling interests, net of contribution, cash	(6)													(6)
Noncontrolling interest, decrease from redemptions or purchase of interests		$ 1	$ 4												$ 1	$ 4
Non-cash adjustments for change in tax basis	20									20
Dividends to common stockholders and distributions to CEG						(63)					(36)								(27)
Balance at end of period at Sep. 30, 2020	2,237							0	1	1,918		(22)	(15)	355
Balance at beginning of period at Dec. 31, 2020	2,715							0	1	1,922		(84)	(14)	890
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(78)											3		(81)
Unrealized gain on derivatives, net of tax	11												4	7
Contributions from, Distributions to CEG, non-cash						27													27
Contributions from CEG, cash						103	126												103	126
Agua Caliente acquisition				$ 273													$ 273
Noncontrolling interest, decrease from redemptions or purchase of interests					$ (118)													$ (118)
Non-cash adjustments for change in tax basis	2									2
Dividends to common stockholders and distributions to CEG						(66)					(38)								(28)
Balance at end of period at Mar. 31, 2021	2,995							0	1	1,886		(81)	(10)	1,199
Balance at beginning of period at Dec. 31, 2020	2,715							0	1	1,922		(84)	(14)	890
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(19)
Balance at end of period at Sep. 30, 2021	2,955							0	1	1,810		(25)	(8)	1,177
Balance at beginning of period at Mar. 31, 2021	2,995							0	1	1,886		(81)	(10)	1,199
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	31											35		(4)
Unrealized gain on derivatives, net of tax	0												1	(1)
Contributions from, Distributions to CEG, non-cash						3													3
Contributions from CEG, cash						1	$ 38												1	$ 38
Stock-based compensation	1									1
Noncontrolling interest, decrease from redemptions or purchase of interests					$ 1													$ 1
Non-cash adjustments for change in tax basis	(1)									(1)
Dividends to common stockholders and distributions to CEG						(66)					(38)								(28)
Balance at end of period at Jun. 30, 2021	3,003							0	1	1,848		(46)	(9)	1,209
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	25											21		3
Unrealized gain on derivatives, net of tax	3												1	2
Contributions from, Distributions to CEG, non-cash						2													2
Distributions from noncontrolling interests, net of contribution, cash	(11)													(11)
Stock-based compensation	1									1
Dividends to common stockholders and distributions to CEG						$ (67)					$ (39)								$ (28)
Balance at end of period at Sep. 30, 2021	2,955							$ 0	$ 1	$ 1,810		$ (25)	$ (8)	$ 1,177
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest, Including Rounding Adjustments	$ 24