Employee Benefit Plans - SPPC (Details) - SPPC - United States - NV Energy - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020
Other Current Liabilities | Other Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Other current liabilities	$ (1)	$ (1)
Other Noncurrent Liabilities | Other Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Other long-term liabilities	(8)	(8)
Other Noncurrent Liabilities | Other Postretirement Plans
Defined Benefit Plan Disclosure [Line Items]
Other long-term liabilities	(14)	(13)
Qualified Plan | Other Assets | Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Other non-current assets	$ 29	$ 26