Retirement Plan and Postretirement Benefits - SPPC (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Other Postretirement Benefits Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Plan Assets, Contributions by Employer	$ 3	$ 2
Assets for Plan Benefits, Defined Benefit Plan	20	76
Liability, Defined Benefit Plan, Noncurrent	(34)	(7)
Other current liabilities	0	0
UNITED STATES | Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Plan Assets, Contributions by Employer	13	12
Assets for Plan Benefits, Defined Benefit Plan	43	73
Liability, Defined Benefit Plan, Noncurrent	(283)	(282)
Other current liabilities	(13)	(13)
Sierra Pacific Power Company [Member] | UNITED STATES | Other Postretirement Benefits Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Plan Assets, Contributions by Employer	0	0	$ 6
Sierra Pacific Power Company [Member] | UNITED STATES | Other Noncurrent Liabilities [Member] | NV Energy, Inc. [Member] | Other Postretirement Benefits Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Liability, Defined Benefit Plan, Noncurrent	(13)	(7)
Sierra Pacific Power Company [Member] | Qualified Plan [Member] | UNITED STATES | Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Plan Assets, Contributions by Employer	0	0	6
Sierra Pacific Power Company [Member] | Qualified Plan [Member] | UNITED STATES | Other Noncurrent Assets [Member] | NV Energy, Inc. [Member] | Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Assets for Plan Benefits, Defined Benefit Plan	26	0
Sierra Pacific Power Company [Member] | Qualified Plan [Member] | UNITED STATES | Other Noncurrent Liabilities [Member] | NV Energy, Inc. [Member] | Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Liability, Defined Benefit Plan, Noncurrent	0	(4)
Sierra Pacific Power Company [Member] | Nonqualified Plan [Member] | UNITED STATES | Other Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Plan Assets, Contributions by Employer	1	1	$ 1
Sierra Pacific Power Company [Member] | Nonqualified Plan [Member] | UNITED STATES | Other Noncurrent Liabilities [Member] | NV Energy, Inc. [Member] | Other Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Liability, Defined Benefit Plan, Noncurrent	(8)	(8)
Sierra Pacific Power Company [Member] | Nonqualified Plan [Member] | UNITED STATES | Other Current Liabilities [Member] | NV Energy, Inc. [Member] | Other Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Other current liabilities	$ (1)	$ (1)