Regulatory Matters - NPC - Regulatory Liabilities (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2016	Dec. 31, 2015
Regulatory Liabilities [Line Items]
Regulatory Liabilities		$ 3,120	$ 3,033
Regulatory liabilities		187	402
Regulatory liabilities		$ 2,933	2,631
Removal Costs [Member]
Regulatory Liabilities [Line Items]
Regulatory liability amortization period years	[1]	27 years
Regulatory Liabilities	[1]	$ 2,242	2,167
Impact fees [Member]
Regulatory Liabilities [Line Items]
Regulatory liability amortization period years		6 years
Regulatory Liabilities		$ 90	0
Regulatory liabilities other [Member]
Regulatory Liabilities [Line Items]
Regulatory liability amortization period years		Various
Regulatory Liabilities		$ 327	301
Nevada Power Company [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		453	477
Regulatory liabilities		37	173
Regulatory liabilities		$ 416	304
Nevada Power Company [Member] | Removal Costs [Member]
Regulatory Liabilities [Line Items]
Regulatory liability amortization period years	[2]	P33Y
Regulatory Liabilities	[2]	$ 294	273
Nevada Power Company [Member] | Impact fees [Member]
Regulatory Liabilities [Line Items]
Regulatory liability amortization period years		P6Y
Regulatory Liabilities		$ 90	0
Nevada Power Company [Member] | Energy Efficiency Program [Member]
Regulatory Liabilities [Line Items]
Regulatory liability amortization period years		P1Y
Regulatory Liabilities		$ 37	34
Nevada Power Company [Member] | Deferred Excess Energy Costs [Member]
Regulatory Liabilities [Line Items]
Regulatory liability amortization period years		P1Y
Regulatory Liabilities		$ 0	139
Nevada Power Company [Member] | Regulatory liabilities other [Member]
Regulatory Liabilities [Line Items]
Regulatory liability amortization period years		Various
Regulatory Liabilities		$ 32	$ 31

[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. Amounts are deducted from rate base or otherwise accrue a carrying cost.