Insurance Claim Reserves (details) Asbestos and Environmental Reserves - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Asbestos reserves [Member]
Liability for claims and claim adjustment expense
Increase (decrease) to asbestos and environmental reserves	$ 224	$ 250	$ 190
Net losses paid	$ 770	$ 242	$ 218
Percent of total asbestos net paid losses related to policyholders with whom the Company had entered into settlement agreements limiting the Company's liability	69.00%	8.00%	1.00%
Environmental reserves [Member]
Liability for claims and claim adjustment expense
Increase (decrease) to asbestos and environmental reserves	$ 72	$ 87	$ 65
Business and International Insurance [Member] | Asbestos reserves [Member]
Liability for claims and claim adjustment expense
Increase (decrease) to asbestos and environmental reserves	224	250	190
Business and International Insurance [Member] | Environmental reserves [Member]
Liability for claims and claim adjustment expense
Increase (decrease) to asbestos and environmental reserves	$ 72	$ 87	$ 65