Revenue from Contracts with Customers Revenue from Contracts with Customers - NPC - Customer Revenue (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	$ 3,516	$ 3,687
Operating revenue	4,527	4,610
Non-contracts with customer revenue [Member]
Disaggregation of Revenue [Line Items]
Operating revenue	118	138
Regulated Operation [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	3,213	3,407
Regulated Operation [Member] | Regulated retail electric [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	2,061	2,156
Nevada Power Company [Member]
Disaggregation of Revenue [Line Items]
Operating revenue	389	395
Nevada Power Company [Member] | Non-contracts with customer revenue [Member]
Disaggregation of Revenue [Line Items]
Operating revenue	6	6
Nevada Power Company [Member] | Regulated Operation [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	383	389
Nevada Power Company [Member] | Regulated Operation [Member] | Regulated retail electric [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	367	372
Nevada Power Company [Member] | Regulated Operation [Member] | Regulated wholesale, transmission and other [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	16	17
Nevada Power Company [Member] | Fully bundled customer [Member] | Regulated Operation [Member] | Regulated retail electric [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	360	365
Nevada Power Company [Member] | Fully bundled customer [Member] | Regulated Operation [Member] | Regulated retail electric [Member] | Residential [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	193	200
Nevada Power Company [Member] | Fully bundled customer [Member] | Regulated Operation [Member] | Regulated retail electric [Member] | Commercial [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	94	90
Nevada Power Company [Member] | Fully bundled customer [Member] | Regulated Operation [Member] | Regulated retail electric [Member] | Industrial [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	70	70
Nevada Power Company [Member] | Fully bundled customer [Member] | Regulated Operation [Member] | Regulated retail electric [Member] | Other [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	3	5
Nevada Power Company [Member] | Distribution only service [Member] | Regulated Operation [Member] | Regulated retail electric [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	$ 7	$ 7