Reinsurance (Narrative) (Details) - USD ($) $ in Billions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Reinsurance Disclosures [Abstract]
Deposit assets in premiums, reinsurance, and other receivables or secondary guarantee risk for reinsurance	$ 1.8	$ 2.5
Deposit liabilities in other liabilities for reinsurance	1.4	1.4
Ceded Credit Risk [Line Items]
Reinsurance recoverables	6.6	6.7
Ceded Credit Risk, Unsecured [Member]
Ceded Credit Risk [Line Items]
Reinsurance recoverables	$ 3.8	3.6
Modified Coinsurance of Closed Block [Member]
Reinsurance Retention Policy [Line Items]
Reinsurance Retention Policy, Reinsured Risk, Percentage	59.25%
Five Largest Ceded Reinsurers [Member]
Ceded Credit Risk [Line Items]
Five largest reinsurers, reinsurance recoverables amount	$ 4.2	$ 4.3
Five largest reinsurers, reinsurance recoverables percentage	64.00%	64.00%
Five Largest Ceded Reinsurers [Member] | Ceded Credit Risk, Unsecured [Member]
Ceded Credit Risk [Line Items]
Five largest reinsurers, reinsurance recoverables amount	$ 2.0	$ 1.7