Reinsurance (Incurred Consolidated Property Casualty Insurance Loss And Loss Expenses On Assumed And Ceded Business) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Net incurred loss and loss expenses	$ 2,856	$ 2,505	$ 2,322
Property, Liability and Casualty Insurance Product Line [Member]
Direct incurred loss and loss expenses	2,661	2,323	2,235
Assumed incurred loss and loss expenses	6	11	6
Ceded incurred loss and loss expenses	(40)	(33)	(104)
Net incurred loss and loss expenses	$ 2,627	$ 2,301	$ 2,137