Schedule V. Valuation and Qualifying Accounts (Schedule of valuation and qualifying accounts) (Details) - Allowance for doubtful accounts, insurance and reinsurance receivables - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Movement in valuation allowances and reserves [Roll Forward]
Balance at Beginning of Period	$ 71	$ 73	$ 83
Charged to Costs and Expenses	(6)	4	(1)
Charged to Other Accounts	0	0	0
Deductions	(8)	(6)	(9)
Balance at End of Period	$ 57	$ 71	$ 73