Revenue from Contracts with Customers Revenue from Contracts with Customers - NPC - Customer Revenue (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	$ 3,317	$ 3,429	$ 6,833	$ 7,116
Operating revenue	4,612	4,894	9,139	9,504
Non-contracts with customer revenue [Member]
Disaggregation of Revenue [Line Items]
Operating revenue	102	138	220	276
Regulated Operation [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	2,969	3,063	6,182	6,470
Regulated Operation [Member] | Regulated retail electric [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	2,172	2,232	4,233	4,388
Nevada Power Company [Member]
Disaggregation of Revenue [Line Items]
Operating revenue	509	527	898	922
Nevada Power Company [Member] | Non-contracts with customer revenue [Member]
Disaggregation of Revenue [Line Items]
Operating revenue	6	7	12	13
Nevada Power Company [Member] | Regulated Operation [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	503	520	886	909
Nevada Power Company [Member] | Regulated Operation [Member] | Regulated retail electric [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	491	506	859	878
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	12	14	27	31
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	485	498	846	863
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	304	266	497	466
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	96	114	190	204
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	83	112	154	182
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	2	6	5	11
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	$ 6	$ 8	$ 13	$ 15