Long-Term Debt (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Senior Medium Term Notes, Par Amount	$ 1,136
Long-term debt, interest rate 3.5%	3.50%
Subordinated Notes Par Amount	$ 588
Capital Lease Obligations	$ 4	$ 0
Long-term Debt, Interest Rate 6.95%	6.95%
Senior medium-term notes	$ 1,147	637
Long-term debt, Parent only maturities	585
Subordinated Debt	$ 572	$ 87
Long-term debt, interest rate 3.35%	3.35%
Senior Notes [Member]
Debt Instrument [Line Items]
Senior Notes	$ 500
Subordinated Notes Interest Rate 6.95 Percent [Member]
Debt Instrument [Line Items]
Subordinated Notes Par Amount	$ 88
New interest rate	3mL+3.89%
Subordinated Debt	$ 87
Subordinated Notes Interest Rate 3.25 Percent [Member]
Debt Instrument [Line Items]
Subordinated Notes Par Amount	500
Subordinated Debt	$ 485