Segments of Operations (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended				6 Months Ended
	Jun. 30, 2013		Jun. 30, 2012		Jun. 30, 2013		Jun. 30, 2012
Segment Reporting Information [Line Items]
Total premiums earned	$ 709		$ 640		$ 1,396		$ 1,243
Net investment income	332		329		658		646
Other income	25		24		47		42
Revenues before realized gains (losses)	1,098		1,109		2,189		2,152
Realized gains on securities	41		16		98		60
Realized losses on subsidiaries	0		(1)		0		(1)
Total revenues	1,139		1,124		2,287		2,211
Property and Casualty Insurance [Member]
Segment Reporting Information [Line Items]
Net investment income	65		69		131		139
Other income	6		8		9		11
Revenues before realized gains (losses)	780		717		1,536		1,393
Annuity [Member]
Segment Reporting Information [Line Items]
Net investment income	257		245		505		473
Other income	15		12		29		25
Revenues before realized gains (losses)	272		257		534		498
Run-off Long-term Care and Life [Member]
Segment Reporting Information [Line Items]
Revenues before realized gains (losses)	47		49		97		96
Medicare Supplement and Critical Illness [Member]
Segment Reporting Information [Line Items]
Revenues before realized gains (losses)	0	[1]	79	[1]		[1]	159	[1]
Other [Member]
Segment Reporting Information [Line Items]
Revenues before realized gains (losses)	(1)		7		22		6
Specialty Property and transportation [Member]
Segment Reporting Information [Line Items]
Total premiums earned	301		290		594		553
Specialty casualty [Member]
Segment Reporting Information [Line Items]
Total premiums earned	277		236		536		456
Specialty financial [Member]
Segment Reporting Information [Line Items]
Total premiums earned	113		98		229		201
Specialty Other [Member]
Segment Reporting Information [Line Items]
Total premiums earned	$ 18		$ 16		$ 37		$ 33

[1] Sold in August 2012.