Reinsurance (Details 3) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Premiums earned:
Direct	$ 5,411	$ 4,969	$ 4,562
Assumed	30	24	21
Ceded	(97)	(95)	(90)
Premiums earned, net	5,344	4,898	4,493
Insurance losses and loss expenses:
Insurance losses and loss expenses, net	3,958	3,467	3,480
Property and casualty insurance operations
Premiums written:
Direct	5,514	5,076	4,631
Assumed	30	26	21
Ceded	(57)	(57)	(49)
Premiums written, net	5,487	5,045	4,603
Premiums earned:
Direct	5,286	4,850	4,449
Assumed	30	24	21
Ceded	(56)	(54)	(48)
Premiums earned, net	5,260	4,820	4,422
Insurance losses and loss expenses:
Direct	3,834	3,366	3,382
Assumed	25	7	10
Ceded	(6)	(13)	(13)
Insurance losses and loss expenses, net	3,853	3,360	3,379
Life insurance operations
Premiums earned:
Direct	125	119	113
Ceded	(41)	(41)	(42)
Premiums earned, net	84	78	71
Insurance losses and loss expenses:
Direct	120	124	120
Ceded	(15)	(17)	(19)
Insurance losses and loss expenses, net	$ 105	$ 107	$ 101