Insurance Claim Reserves Insurance Claim Reserves (Details) - Asbestos and Environmental Reserves - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Liability for claims and claim adjustment expense
Asbestos and environmental claims reserves, balance	$ 1,620	$ 1,640
Asbestos reserves [Member]
Liability for claims and claim adjustment expense
Increase to asbestos and environmental claims	225	225	$ 225
Net losses paid	$ 225	$ 271	$ 708
Percent of total asbestos net paid losses related to policyholders with whom the Company had entered into settlement agreements limiting the Company's liability	9.00%	4.00%	69.00%
Asbestos reserves [Member] | PPG Industries, Inc Litigation [Member]
Liability for claims and claim adjustment expense
Settlement amount paid			$ 458
Environmental reserves [Member]
Liability for claims and claim adjustment expense
Increase to asbestos and environmental claims	$ 55	$ 65	$ 82