Asset Retirement Obligations - NPC - Asset Retirement Obligation by Type (Details) - USD ($) $ in Millions		Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Asset Retirement Obligations By Type [Line Items]
Regulatory Liabilities		$ 7,311	$ 7,506
Asset Retirement Obligation		1,272	985	$ 954
Other Plant in Service [Member]
Asset Retirement Obligations By Type [Line Items]
Asset Retirement Obligation		44	42
Cost of removal
Asset Retirement Obligations By Type [Line Items]
Regulatory Liabilities	[1]	2,370	2,426
Nevada Power Company [Member]
Asset Retirement Obligations By Type [Line Items]
Regulatory Liabilities		1,256	1,186
Asset Retirement Obligation		74	83	$ 80
Nevada Power Company [Member] | Waste water remediation [Member]
Asset Retirement Obligations By Type [Line Items]
Asset Retirement Obligation		37	37
Nevada Power Company [Member] | Evaporative Ponds and Dry Ash Landfills [Member]
Asset Retirement Obligations By Type [Line Items]
Asset Retirement Obligation		12	12
Nevada Power Company [Member] | Asbestos [Member]
Asset Retirement Obligations By Type [Line Items]
Asset Retirement Obligation		0	5
Nevada Power Company [Member] | Solar [Member]
Asset Retirement Obligations By Type [Line Items]
Asset Retirement Obligation		2	2
Nevada Power Company [Member] | Other Plant in Service [Member]
Asset Retirement Obligations By Type [Line Items]
Asset Retirement Obligation		23	27
Nevada Power Company [Member] | Cost of removal
Asset Retirement Obligations By Type [Line Items]
Regulatory Liabilities	[2]	$ 332	$ 320

[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 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.