Revenue from Contract with Customer Revenue from Contract with Customer - NPC (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax									$ 14,837	$ 14,972
Revenues									19,844	19,787	$ 18,614
Non-contracts with customer revenue [Member]
Disaggregation of Revenue [Line Items]
Revenues									534	601
Regulated Operation [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax									13,433	13,612
Regulated Operation [Member] | Regulated retail electric [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax									9,465	9,419
Regulated Operation [Member] | Regulated retail gas [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax									686	737
Nevada Power Company [Member]
Disaggregation of Revenue [Line Items]
Revenues	$ 420	$ 806	$ 527	$ 395	$ 407	$ 820	$ 562	$ 395	2,148	2,184	$ 2,206
Nevada Power Company [Member] | Non-contracts with customer revenue [Member]
Disaggregation of Revenue [Line Items]
Revenues									25	24
Nevada Power Company [Member] | Regulated Operation [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax									2,123	2,160
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									57	53
Nevada Power Company [Member] | Regulated Operation [Member] | Fully bundled customer [Member] | Regulated retail electric [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax									2,035	2,077
Nevada Power Company [Member] | Regulated Operation [Member] | Fully bundled customer [Member] | Residential [Member] | Regulated retail electric [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax									1,141	1,195
Nevada Power Company [Member] | Regulated Operation [Member] | Fully bundled customer [Member] | Commercial [Member] | Regulated retail electric [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax									441	433
Nevada Power Company [Member] | Regulated Operation [Member] | Fully bundled customer [Member] | Industrial [Member] | Regulated retail electric [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax									433	425
Nevada Power Company [Member] | Regulated Operation [Member] | Fully bundled customer [Member] | Other [Member] | Regulated retail electric [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax									20	24
Nevada Power Company [Member] | Regulated Operation [Member] | Distribution only service [Member] | Regulated retail electric [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax									31	30
Nevada Power Company [Member] | Regulated Operation [Member] | Fully bundled and distribution services only customer [Member] | Regulated retail electric [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax									$ 2,066	$ 2,107