Segments of Operations (Details 1) (USD $) In Millions, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012		Dec. 31, 2011	Dec. 31, 2010
Segment Reporting Information [Line Items]
Total premiums earned									$ 2,847		$ 2,759	$ 2,550
Investment income									1,312		1,241	1,191
Other income									183		175	194
Revenues before realized gains (losses)									4,691		4,677	4,409
Realized gains (losses) on securities									210		76	101
Realized gains (losses) on subsidiaries									161		(3)	(13)
Total revenues	1,236	1,563	1,150	1,113	1,283	1,335	1,093	1,039	5,062		4,750	4,497
Property and Casualty Insurance [Member]
Segment Reporting Information [Line Items]
Investment income									279		296	341
Other income									67		65	64
Revenues before realized gains (losses)									3,193		3,120	2,955
Annuity [Member]
Segment Reporting Information [Line Items]
Investment income									982		868	788
Other income									85		73	70
Revenues before realized gains (losses)									1,067		941	858
Run-off Long-term Care and Life [Member]
Segment Reporting Information [Line Items]
Revenues before realized gains (losses)									212		212	218
Medicare Supplement and Critical Illness [Member]
Segment Reporting Information [Line Items]
Revenues before realized gains (losses)									212	[1]	325	341
Other [Member]
Segment Reporting Information [Line Items]
Revenues before realized gains (losses)									7		79	37
Specialty Property and transportation [Member]
Segment Reporting Information [Line Items]
Total premiums earned									1,423		1,412	1,167
Specialty casualty [Member]
Segment Reporting Information [Line Items]
Total premiums earned									948		872	873
Specialty financial [Member]
Segment Reporting Information [Line Items]
Total premiums earned									405		408	446
Specialty Other [Member]
Segment Reporting Information [Line Items]
Total premiums earned									$ 71		$ 67	$ 64

[1] Sold in August 2012.