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Summary of Significant Accounting Policies (Details) - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2021
Dec. 31, 2020
Regulatory Assets and Liabilities Disclosure [Abstract]    
Regulatory Assets, Current $ 111 $ 64
Regulatory Assets, Noncurrent 415 442
Total regulated assets 526 506
Regulatory Liabilities, Current 56 59
Regulatory Liabilities, Noncurrent 1,324 1,314
Total regulated liabilities $ 1,380 $ 1,373
Interest Capitalized [Abstract]    
Minimum period of construction for capitalization of interest 3 months  
Minimum total project cost for capitalization of interest $ 1  
Retirement Benefits, Description [Abstract]    
Threshold For Amortization Of Unrecognized Actuarial Gains Losses 10.00%  
Pension Benefits [Member]    
Retirement Benefits, Description [Abstract]    
Approximate Amortization Period Of Net Actuarial Gain Loss 10 years  
Amortization Period Of Difference Between Expected And Actual Return On Plan Assets 5 years  
Other Postretirement Benefits [Member]    
Retirement Benefits, Description [Abstract]    
Approximate Amortization Period Of Net Actuarial Gain Loss 5 years  
Minimum [Member]    
Leases [Abstract]    
Lessee, Operating Lease, Term of Contract 1 year  
Minimum [Member] | Pension Benefits [Member]    
Retirement Benefits, Description [Abstract]    
Threshold For Market Related Value 90.00%  
Maximum [Member]    
Leases [Abstract]    
Lessee, Operating Lease, Term of Contract 20 years  
Maximum [Member] | Pension Benefits [Member]    
Retirement Benefits, Description [Abstract]    
Threshold For Market Related Value 110.00%