Reserve for Property-Liability Insurance Claims and Claims Expense (Details 2) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Total auto
Increase (decrease) in claims and claims expense
Net increase (decrease) to reserves	$ (237)	$ (365)	$ (381)
Catastrophes
Increase (decrease) in claims and claims expense
Losses from catastrophes, net of recoveries	1,250	2,350	3,820
Reserve reestimates | Other personal lines
Increase (decrease) in claims and claims expense
Net increase (decrease) to reserves	(21)	(30)	94
Reserve reestimates | Discontinued Lines and Coverages
Increase (decrease) in claims and claims expense
Net increase (decrease) to reserves	142	51	21
Catastrophe loss reestimates
Increase (decrease) in claims and claims expense
Net increase (decrease) to reserves	88	410	130
Catastrophe loss reestimates | Homeowners
Increase (decrease) in claims and claims expense
Net increase (decrease) to reserves		(321)	(69)
Non-catastrophes loss reestimates | Homeowners
Increase (decrease) in claims and claims expense
Net increase (decrease) to reserves	$ (5)