Summary of Significant Accounting and Reporting Policies - Noncontrolling Interests (Details) - USD ($)	3 Months Ended						9 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2020	Sep. 30, 2019
Stockholders' Equity Attributable to Noncontrolling Interest [Roll Forward]
Balances, beginning of period			$ 4,883,000,000				$ 4,883,000,000
Related party note receivable		$ 1,000,000			$ 1,000,000
Sale of noncontrolling interest in a NEP OpCo subsidiary					893,000,000
Net income (loss) attributable to NCI	$ 138,000,000			$ (173,000,000)			(284,000,000)	$ (380,000,000)
Related party contributions	1,000,000	2,000,000	3,000,000		11,000,000	$ 1,000,000
Related party distributions	(81,000,000)	(69,000,000)	(62,000,000)	(71,000,000)	(56,000,000)	(51,000,000)
Changes in non-economic ownership interests	(7,000,000)			(6,000,000)		(6,000,000)
Differential membership investment contributions, net of distributions				11,000,000	472,000,000
Payments to Class B noncontrolling interest investors	(13,000,000)	(11,000,000)	(10,000,000)	(7,000,000)	(3,000,000)	(5,000,000)
Other	(1,000,000)	(1,000,000)	(1,000,000)	0	1,000,000	1,000,000
Balances, end of period	4,425,000,000						4,425,000,000
Class B Noncontrolling Ownership Interests [Member]
Stockholders' Equity Attributable to Noncontrolling Interest [Roll Forward]
Balances, beginning of period	2,712,000,000	2,670,000,000	2,628,000,000	1,673,000,000	758,000,000	751,000,000	2,628,000,000	751,000,000
Sale of noncontrolling interest in a NEP OpCo subsidiary					893,000,000
Net income (loss) attributable to NCI	55,000,000	53,000,000	52,000,000	34,000,000	25,000,000	12,000,000
Payments to Class B noncontrolling interest investors	(13,000,000)	(11,000,000)	(10,000,000)	(7,000,000)	(3,000,000)	(5,000,000)
Balances, end of period	2,754,000,000	2,712,000,000	2,670,000,000	1,700,000,000	1,673,000,000	758,000,000	2,754,000,000	1,700,000,000
Differential Membership Interests [Member]
Stockholders' Equity Attributable to Noncontrolling Interest [Roll Forward]
Balances, beginning of period	1,681,000,000	1,767,000,000	1,798,000,000	1,912,000,000	1,983,000,000	2,019,000,000	1,798,000,000	2,019,000,000
Net income (loss) attributable to NCI	(56,000,000)	(78,000,000)	(71,000,000)	(64,000,000)	(63,000,000)	(60,000,000)
Differential membership investment contributions, net of distributions	39,000,000	(8,000,000)	40,000,000	27,000,000	(8,000,000)	24,000,000
Other	(1,000,000)
Balances, end of period	1,663,000,000	1,681,000,000	1,767,000,000	1,875,000,000	1,912,000,000	1,983,000,000	1,663,000,000	1,875,000,000
NEER's Noncontrolling Ownership Interests in NEP OpCo and Silver State [Member]
Stockholders' Equity Attributable to Noncontrolling Interest [Roll Forward]
Balances, beginning of period	(97,000,000)	(130,000,000)	389,000,000	612,000,000	241,000,000	342,000,000	389,000,000	342,000,000
Related party note receivable		1,000,000			1,000,000
Acquisition of subsidiary with noncontrolling ownership interests				(10,000,000)	472,000,000
Net income (loss) attributable to NCI	126,000,000	97,000,000	(459,000,000)	(143,000,000)	(59,000,000)	(50,000,000)
Other comprehensive income (loss)		1,000,000				(3,000,000)
Related party contributions					11,000,000	1,000,000
Related party distributions	(79,000,000)	(67,000,000)	(60,000,000)	(69,000,000)	(54,000,000)	(50,000,000)
Changes in non-economic ownership interests	0			0
Other	0	1,000,000				1,000,000
Balances, end of period	(50,000,000)	(97,000,000)	(130,000,000)	390,000,000	612,000,000	241,000,000	(50,000,000)	390,000,000
Other Noncontrolling Interest [Member]
Stockholders' Equity Attributable to Noncontrolling Interest [Roll Forward]
Balances, beginning of period	53,000,000	47,000,000	68,000,000	59,000,000	66,000,000	80,000,000	68,000,000	80,000,000
Net income (loss) attributable to NCI	13,000,000	6,000,000	(22,000,000)	0	(5,000,000)	(7,000,000)
Other comprehensive income (loss)		0				0
Related party contributions	1,000,000	2,000,000	3,000,000
Related party distributions	(2,000,000)	(2,000,000)	(2,000,000)	(2,000,000)	(2,000,000)	(1,000,000)
Changes in non-economic ownership interests	(7,000,000)			(6,000,000)		(6,000,000)
Balances, end of period	58,000,000	53,000,000	47,000,000	51,000,000	59,000,000	66,000,000	58,000,000	51,000,000
Non-controlling Interests [Member]
Stockholders' Equity Attributable to Noncontrolling Interest [Roll Forward]
Balances, beginning of period	4,349,000,000	4,354,000,000	4,883,000,000	4,256,000,000	3,048,000,000	3,192,000,000	4,883,000,000	3,192,000,000
Related party note receivable		1,000,000			1,000,000
Sale of noncontrolling interest in a NEP OpCo subsidiary					893,000,000
Acquisition of subsidiary with noncontrolling ownership interests				(10,000,000)	472,000,000
Net income (loss) attributable to NCI	138,000,000	78,000,000	(500,000,000)	(173,000,000)	(102,000,000)	(105,000,000)
Other comprehensive income (loss)		1,000,000				(3,000,000)
Related party contributions	1,000,000	2,000,000	3,000,000		11,000,000	1,000,000
Related party distributions	(81,000,000)	(69,000,000)	(62,000,000)	(71,000,000)	(56,000,000)	(51,000,000)
Changes in non-economic ownership interests	(7,000,000)			(6,000,000)		(6,000,000)
Differential membership investment contributions, net of distributions	39,000,000	(8,000,000)	40,000,000	27,000,000	(8,000,000)	24,000,000
Payments to Class B noncontrolling interest investors	(13,000,000)	(11,000,000)	(10,000,000)	(7,000,000)	(3,000,000)	(5,000,000)
Other	(1,000,000)	1,000,000				1,000,000
Balances, end of period	$ 4,425,000,000	$ 4,349,000,000	$ 4,354,000,000	$ 4,016,000,000	$ 4,256,000,000	$ 3,048,000,000	$ 4,425,000,000	$ 4,016,000,000