Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	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	Dec. 31, 2019
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	$ 6,283,000	$ 6,279,000	$ 7,066,000	$ 6,500,000	$ 5,345,000	$ 5,538,000	$ 7,066,000	$ 5,538,000
Amounts reclassified from AOCI to interest expense						(6,000)
Other comprehensive income related to equity method investee		1,000				1,000
Total other comprehensive income (loss), net of tax	0	1,000	0	0	0	(5,000)	1,000	(5,000)
Ending balance	6,723,000	6,283,000	6,279,000	6,176,000	6,500,000	5,345,000	6,723,000	6,176,000
Noncontrolling interests	4,425,000						4,425,000		$ 4,883,000
Total
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	(21,000)	(22,000)	(22,000)	(23,000)	(23,000)	(18,000)	(22,000)	(18,000)
Ending balance	(21,000)	(21,000)	(22,000)	(23,000)	(23,000)	(23,000)	(21,000)	(23,000)
Net Unrealized Gains (Losses) on Cash Flow Hedges [Member]
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	0	0	0	0	0	6,000	0	6,000
Amounts reclassified from AOCI to interest expense						(6,000)
Other comprehensive income related to equity method investee		0				0
Total other comprehensive income (loss), net of tax	0	0	0	0	0	(6,000)
Ending balance	0	0	0	0	0	0	0	0
Noncontrolling interests	0			0			0	0
AOCI attributable to NEP	0			0			0	0
Other Comprehensive Income (Loss) Related to Equity Method Investee [Member]
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	(21,000)	(22,000)	(22,000)	(23,000)	(23,000)	(24,000)	(22,000)	(24,000)
Amounts reclassified from AOCI to interest expense						0
Other comprehensive income related to equity method investee		1,000				1,000
Total other comprehensive income (loss), net of tax	0	1,000	0	0	0	1,000
Ending balance	(21,000)	$ (21,000)	$ (22,000)	(23,000)	$ (23,000)	$ (23,000)	(21,000)	(23,000)
Noncontrolling interests	(13,000)			(15,000)			(13,000)	(15,000)
AOCI attributable to NEP	(8,000)			(8,000)			(8,000)	(8,000)
Total Attributable to Noncontrolling Interest [Member]
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Noncontrolling interests	(13,000)			(15,000)			(13,000)	(15,000)
Total Attributable to Parent [Member]
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
AOCI attributable to NEP	$ (8,000)			$ (8,000)			$ (8,000)	$ (8,000)