XML 149 R103.htm IDEA: XBRL DOCUMENT v3.8.0.1
Employee Benefit Plans - SPPC - Amounts Payable (Details) - Sierra Pacific Power Company [Member] - NV Energy, Inc. [Member] - USD ($)
$ in Millions
Mar. 31, 2018
Dec. 31, 2017
Other Noncurrent Liabilities [Member] | Other Postretirement Benefits Plan [Member]    
Defined Benefit Plan Disclosure [Line Items]    
Liability, Defined Benefit Plan, Noncurrent $ 20 $ 20
Domestic Plan [Member] | Other Noncurrent Liabilities [Member] | Pension Plan [Member]    
Defined Benefit Plan Disclosure [Line Items]    
Liability, Defined Benefit Plan, Noncurrent 2 2
Domestic Plan [Member] | Other Noncurrent Liabilities [Member] | Other Pension Plan [Member]    
Defined Benefit Plan Disclosure [Line Items]    
Liability, Defined Benefit Plan, Noncurrent 8 8
Domestic Plan [Member] | Other Current Liabilities [Member] | Other Pension Plan [Member]    
Defined Benefit Plan Disclosure [Line Items]    
Liability, Defined Benefit Plan, Current $ 1 $ 1