Insurance (Details 2) (Property and casualty insurance [Member], USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Property and casualty insurance [Member]
Effects of Reinsurance [Line Items]
Direct premiums written	$ 4,744	$ 4,283	$ 4,061
Reinsurance assumed	61	38	45
Reinsurance ceded	(1,464)	(1,372)	(1,336)
Net written premiums	3,341	2,949	2,770
Direct premiums earned	4,684	4,120	4,062
Reinsurance assumed	45	36	41
Reinsurance ceded	(1,525)	(1,309)	(1,344)
Net earned premiums	3,204	2,847	2,759
Reinsurance recoveries	$ 1,255	$ 1,743	$ 770