Dividend and Other Capital-Related Restrictions (Details) $ in Billions	Dec. 31, 2019 USD ($)
Dividend and Other Capital-Related Restrictions [Abstract]
Equity to total capitalization ratio, low end of range (in hundredths)	47.10%
Equity to total capitalization ratio, high end of range (in hundredths)	57.50%
Equity to total capitalization ratio	52.30%
Unrestricted Retained Earnings Per State Regulatory Commissions Dividend Restrictions	$ 1.1
Capitalization, Short term debt, long term debt and equity	11.6
Maximum total capitalization	$ 12.7