Revenue from Contracts with Customers - SPPC - Customer Revenue (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Disaggregation of Revenue [Line Items]
Total Customer Revenue	$ 4,712	$ 3,516
Operating revenue	6,081	4,527
Non-contracts with customer revenue [Member]
Disaggregation of Revenue [Line Items]
Operating revenue	137	118
Regulated Operation [Member]
Disaggregation of Revenue [Line Items]
Total Customer Revenue	4,094	3,213
Regulated Operation [Member] | Regulated retail electric [Member]
Disaggregation of Revenue [Line Items]
Total Customer Revenue	2,108	2,061
Regulated Operation [Member] | Regulated retail gas [Member]
Disaggregation of Revenue [Line Items]
Total Customer Revenue	498	234
Sierra Pacific Power Company [Member]
Disaggregation of Revenue [Line Items]
Operating revenue	220	232
Sierra Pacific Power Company [Member] | Non-contracts with customer revenue [Member]
Disaggregation of Revenue [Line Items]
Operating revenue	1	2
Sierra Pacific Power Company [Member] | Regulated Electric [Member]
Disaggregation of Revenue [Line Items]
Operating revenue	181	184
Sierra Pacific Power Company [Member] | Regulated Electric [Member] | Non-contracts with customer revenue [Member]
Disaggregation of Revenue [Line Items]
Operating revenue	0	1
Sierra Pacific Power Company [Member] | Regulated Gas [Member]
Disaggregation of Revenue [Line Items]
Operating revenue	39	48
Sierra Pacific Power Company [Member] | Regulated Gas [Member] | Non-contracts with customer revenue [Member]
Disaggregation of Revenue [Line Items]
Operating revenue	1	1
Sierra Pacific Power Company [Member] | Regulated Operation [Member]
Disaggregation of Revenue [Line Items]
Total Customer Revenue	219	230
Sierra Pacific Power Company [Member] | Regulated Operation [Member] | Regulated wholesale, transmission and other [Member]
Disaggregation of Revenue [Line Items]
Total Customer Revenue	15	14
Sierra Pacific Power Company [Member] | Regulated Operation [Member] | Regulated Electric [Member]
Disaggregation of Revenue [Line Items]
Total Customer Revenue	181	183
Sierra Pacific Power Company [Member] | Regulated Operation [Member] | Regulated Electric [Member] | Regulated wholesale, transmission and other [Member]
Disaggregation of Revenue [Line Items]
Total Customer Revenue	15	14
Sierra Pacific Power Company [Member] | Regulated Operation [Member] | Regulated Gas [Member]
Disaggregation of Revenue [Line Items]
Total Customer Revenue	38	47
Sierra Pacific Power Company [Member] | Regulated Operation [Member] | Regulated Gas [Member] | Regulated wholesale, transmission and other [Member]
Disaggregation of Revenue [Line Items]
Total Customer Revenue	0	0
Sierra Pacific Power Company [Member] | Regulated Operation [Member] | Fully bundled customer [Member]
Disaggregation of Revenue [Line Items]
Total Customer Revenue	203	215
Sierra Pacific Power Company [Member] | Regulated Operation [Member] | Fully bundled customer [Member] | Residential [Member]
Disaggregation of Revenue [Line Items]
Total Customer Revenue	96	99
Sierra Pacific Power Company [Member] | Regulated Operation [Member] | Fully bundled customer [Member] | Commercial [Member]
Disaggregation of Revenue [Line Items]
Total Customer Revenue	64	70
Sierra Pacific Power Company [Member] | Regulated Operation [Member] | Fully bundled customer [Member] | Industrial [Member]
Disaggregation of Revenue [Line Items]
Total Customer Revenue	42	45
Sierra Pacific Power Company [Member] | Regulated Operation [Member] | Fully bundled customer [Member] | Other [Member]
Disaggregation of Revenue [Line Items]
Total Customer Revenue	1	1
Sierra Pacific Power Company [Member] | Regulated Operation [Member] | Fully bundled customer [Member] | Regulated Electric [Member] | Regulated retail electric [Member]
Disaggregation of Revenue [Line Items]
Total Customer Revenue	165	168
Sierra Pacific Power Company [Member] | Regulated Operation [Member] | Fully bundled customer [Member] | Regulated Electric [Member] | Regulated retail electric [Member] | Residential [Member]
Disaggregation of Revenue [Line Items]
Total Customer Revenue	71	69
Sierra Pacific Power Company [Member] | Regulated Operation [Member] | Fully bundled customer [Member] | Regulated Electric [Member] | Regulated retail electric [Member] | Commercial [Member]
Disaggregation of Revenue [Line Items]
Total Customer Revenue	54	57
Sierra Pacific Power Company [Member] | Regulated Operation [Member] | Fully bundled customer [Member] | Regulated Electric [Member] | Regulated retail electric [Member] | Industrial [Member]
Disaggregation of Revenue [Line Items]
Total Customer Revenue	39	41
Sierra Pacific Power Company [Member] | Regulated Operation [Member] | Fully bundled customer [Member] | Regulated Electric [Member] | Regulated retail electric [Member] | Other [Member]
Disaggregation of Revenue [Line Items]
Total Customer Revenue	1	1
Sierra Pacific Power Company [Member] | Regulated Operation [Member] | Fully bundled customer [Member] | Regulated Gas [Member] | Regulated retail gas [Member]
Disaggregation of Revenue [Line Items]
Total Customer Revenue	38	47
Sierra Pacific Power Company [Member] | Regulated Operation [Member] | Fully bundled customer [Member] | Regulated Gas [Member] | Regulated retail gas [Member] | Residential [Member]
Disaggregation of Revenue [Line Items]
Total Customer Revenue	25	30
Sierra Pacific Power Company [Member] | Regulated Operation [Member] | Fully bundled customer [Member] | Regulated Gas [Member] | Regulated retail gas [Member] | Commercial [Member]
Disaggregation of Revenue [Line Items]
Total Customer Revenue	10	13
Sierra Pacific Power Company [Member] | Regulated Operation [Member] | Fully bundled customer [Member] | Regulated Gas [Member] | Regulated retail gas [Member] | Industrial [Member]
Disaggregation of Revenue [Line Items]
Total Customer Revenue	3	4
Sierra Pacific Power Company [Member] | Regulated Operation [Member] | Fully bundled customer [Member] | Regulated Gas [Member] | Regulated retail gas [Member] | Other [Member]
Disaggregation of Revenue [Line Items]
Total Customer Revenue	0	0
Sierra Pacific Power Company [Member] | Regulated Operation [Member] | Distribution only service [Member]
Disaggregation of Revenue [Line Items]
Total Customer Revenue	1	1
Sierra Pacific Power Company [Member] | Regulated Operation [Member] | Distribution only service [Member] | Regulated Electric [Member] | Regulated retail electric [Member]
Disaggregation of Revenue [Line Items]
Total Customer Revenue	1	1
Sierra Pacific Power Company [Member] | Regulated Operation [Member] | Distribution only service [Member] | Regulated Gas [Member] | Regulated retail gas [Member]
Disaggregation of Revenue [Line Items]
Total Customer Revenue	0	0
Sierra Pacific Power Company [Member] | Regulated Operation [Member] | Fully bundled and distribution services only customer [Member]
Disaggregation of Revenue [Line Items]
Total Customer Revenue	204	216
Sierra Pacific Power Company [Member] | Regulated Operation [Member] | Fully bundled and distribution services only customer [Member] | Regulated Electric [Member] | Regulated retail electric [Member]
Disaggregation of Revenue [Line Items]
Total Customer Revenue	166	169
Sierra Pacific Power Company [Member] | Regulated Operation [Member] | Fully bundled and distribution services only customer [Member] | Regulated Gas [Member] | Regulated retail gas [Member]
Disaggregation of Revenue [Line Items]
Total Customer Revenue	$ 38	$ 47