Insurance Claim Reserves (details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Insurance Claim Reserves disclosure
Amount of decrease in gross claims and claim adjustment expense reserves	$ 1,550	$ 1,040
Amount of decline in reinsurance recoverables on unpaid losses	339	492
Accretion of discount	51	50	$ 48
Asbestos and environmental claims reserves, balance	$ 2,170	$ 2,700