Schedule VI Supplementary Information Concerning Property and Casualty Insurance Operations (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Property and Casualty Insurance Products
SEC Schedule, 12-18, Supplemental Information, Property-Casualty Insurance Underwriters [Line Items]
Discount Deducted From Liabilities	$ 388	$ 410	$ 483
Weighted average interest rate	2.98%	3.06%	3.11%
Property and Casualty Insurance Products
SEC Schedule, 12-18, Supplemental Information, Property-Casualty Insurance Underwriters [Line Items]
Losses and Loss Adjustment Expenses Incurred Related to: Current Year	$ 7,107	$ 7,381	$ 6,990
Losses and Loss Adjustment Expenses Incurred Related to: Prior Year	(167)	(41)	457
Paid Losses and Loss Adjustment Expenses	$ 6,406	$ 6,579	$ 6,968