Segments of Operations (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Segment Reporting Information [Line Items]
Total premiums earned	$ 1,132	$ 949	$ 2,817	$ 2,345
Net investment income	377	338	1,117	996
Other income	28	24	75	71
Revenues before realized gains (losses)	1,568	1,387	4,140	3,576
Realized gains on securities	13	56	44	154
Total revenues	1,581	1,443	4,184	3,730
Property and Casualty Insurance [Member]
Segment Reporting Information [Line Items]
Net investment income	76	65	219	196
Other income	4	1	8	10
Revenues before realized gains (losses)	1,212	1,015	3,044	2,551
Annuity [Member]
Segment Reporting Information [Line Items]
Net investment income	287	259	851	764
Other income	20	17	57	46
Revenues before realized gains (losses)	307	276	908	810
Run-off Long-term Care and Life [Member]
Segment Reporting Information [Line Items]
Revenues before realized gains (losses)	48	50	147	147
Other [Member]
Segment Reporting Information [Line Items]
Revenues before realized gains (losses)	1	46	41	68
Specialty Property and transportation [Member]
Segment Reporting Information [Line Items]
Total premiums earned	504	517	1,129	1,111
Specialty casualty [Member]
Segment Reporting Information [Line Items]
Total premiums earned	486	289	1,266	825
Specialty financial [Member]
Segment Reporting Information [Line Items]
Total premiums earned	115	121	348	350
Specialty Other [Member]
Segment Reporting Information [Line Items]
Total premiums earned	$ 27	$ 22	$ 74	$ 59