Reinsurance (Earned Consolidated Property Casualty Insurance Premiums On Assumed And Ceded Business) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Reinsurance Premiums for Insurance Companies, by Product Segment [Line Items]
Direct earned premiums	$ 4,667	$ 4,468	$ 4,151
Assumed earned premiums	29	12	11
Ceded earned premiums	(216)	(237)	(260)
Property, Liability and Casualty Insurance Product Line [Member]
Reinsurance Premiums for Insurance Companies, by Product Segment [Line Items]
Direct earned premiums	4,396	4,209	3,903
Assumed earned premiums	29	12	11
Ceded earned premiums	(154)	(176)	(201)
Net earned premiums	$ 4,271	$ 4,045	$ 3,713