Borrowings and Other Financing Instruments Borrowings and Other Financing Instruments, Dividend and Other Capital-Related Restrictions (Details) $ in Millions	Dec. 31, 2021 USD ($)
Dividend and Other Capital-Related Restrictions [Abstract]
Minimum calendar year average equity to total capitalization ratio authorized by state commission	52.50%
Equity to total capitalization ratio	52.80%
Unrestricted Retained Earnings Per State Regulatory Commissions Dividend Restrictions	$ 11
Total Capitalization	$ 2,091