Insurance Claim Reserves (details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Insurance Claim Reserves disclosure
Amount of increase in gross claims and claim adjustment expense reserves	$ 1,800
Amount of increase in reinsurance recoverables on unpaid losses	155
Accretion of discount	$ 38	$ 38