Reinsurance (Incurred Consolidated Property Casualty Insurance Loss And Loss Expenses On Assumed And Ceded Business) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Net incurred loss and loss expenses	$ 2,808	$ 2,856	$ 2,505
Property, Liability and Casualty Insurance Product Line [Member]
Direct incurred loss and loss expenses	2,596	2,661	2,323
Assumed incurred loss and loss expenses	12	6	11
Ceded incurred loss and loss expenses	(36)	(40)	(33)
Net incurred loss and loss expenses	$ 2,572	$ 2,627	$ 2,301