Commitments and Contingencies - NPC - Legal (Details) - Nevada Power Company [Member] - MW	12 Months Ended		36 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
557 Megawatts of Coal Energy [Member]
Loss Contingencies [Line Items]
Coal-Fired Power Plant Capacity		557
255 Megawatts of Coal Energy [Member]
Loss Contingencies [Line Items]
Coal-Fired Power Plant Capacity	255
536 Megawatts of Renewable Energy [Member]
Loss Contingencies [Line Items]
New Generation Capacity			536
200 Megawatts of Solar Renewable Energy [Member]
Loss Contingencies [Line Items]
New Generation Capacity			200
15 Megawatts of Solar Renewable Energy [Member]
Loss Contingencies [Line Items]
New Generation Capacity			15
35 Megawatts of Renewable Energy [Member]
Loss Contingencies [Line Items]
New Generation Capacity	35