Regulatory Matters - NPC - Regulatory Liabilities (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Regulatory Liabilities [Line Items]
Regulatory Liabilities		$ 7,475	$ 7,311
Regulatory Liability, Current		254	211
Regulatory Liability, Noncurrent		$ 7,221	$ 7,100
Federal statutory income tax rate		21.00%	21.00%	21.00%	35.00%
Tax Cuts and Jobs Act of 2017 [Member]
Regulatory Liabilities [Line Items]
Federal statutory income tax rate					21.00%
Cost of removal
Regulatory Liabilities [Line Items]
Regulatory Liabilities	[1]	$ 2,435	$ 2,370
Other
Regulatory Liabilities [Line Items]
Regulatory Liabilities		854	785
Nevada Power Company [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		1,213	1,256
Regulatory Liability, Current		50	93
Regulatory Liability, Noncurrent		$ 1,163	$ 1,163
Federal statutory income tax rate		21.00%	21.00%	21.00%
Nevada Power Company [Member] | Tax Cuts and Jobs Act of 2017 [Member]
Regulatory Liabilities [Line Items]
Federal statutory income tax rate		21.00%			35.00%
Nevada Power Company [Member] | Deferred income taxes
Regulatory Liabilities [Line Items]
Regulatory Liabilities	[2]	$ 647	$ 681
Nevada Power Company [Member] | Cost of removal
Regulatory Liabilities [Line Items]
Regulatory Liability, Amortization Period	[3]	32 years
Regulatory Liabilities	[3]	$ 340	332
Nevada Power Company [Member] | Impact fees
Regulatory Liabilities [Line Items]
Regulatory Liability, Amortization Period	[4]	2 years
Regulatory Liabilities	[4]	$ 54	72
Nevada Power Company [Member] | Other
Regulatory Liabilities [Line Items]
Regulatory Liabilities		$ 172	$ 171

[1] Amounts represent estimated costs, as accrued through depreciation rates and exclusive of ARO liabilities, of removing regulated property, plant and equipment in accordance with accepted regulatory practices. Amounts are deducted from rate base or otherwise accrue a carrying cost.

[2] Amounts primarily represent income tax liabilities related to the federal tax rate change from 35% to 21% that are probable to be passed on to customers, offset by income tax benefits related to accelerated tax depreciation and certain property-related basis differences that were previously passed on to customers and will be included in regulated rates when the temporary differences reverse.

[3] Amounts represent estimated costs, as accrued through depreciation rates and exclusive of ARO liabilities, of removing regulated property, plant and equipment in accordance with accepted regulatory practices.

[4] Amounts reduce rate base or otherwise accrue a carrying cost.