Segment Information (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Segment Reporting Information [Line Items]
Net income (loss)	$ 401	$ 60	$ 396	$ 594
Property & Casualty Commercial [Member]
Segment Reporting Information [Line Items]
Net income (loss)	164	53	502	494
Group Benefits [Member]
Segment Reporting Information [Line Items]
Net income (loss)	30	25	83	77
Consumer Markets [Member]
Segment Reporting Information [Line Items]
Net income (loss)	94	(16)	152	(80)
Individual Life [Member]
Segment Reporting Information [Line Items]
Net income (loss)	11	(9)	66	55
Retirement Plans [Member]
Segment Reporting Information [Line Items]
Net income (loss)	(7)	(23)	9	9
Mutual Funds [Member]
Segment Reporting Information [Line Items]
Net income (loss)	18	24	56	79
Life Other Operations [Member]
Segment Reporting Information [Line Items]
Net income (loss)	145	105	344	439
Property & Casualty Other Operations [Member]
Segment Reporting Information [Line Items]
Net income (loss)	24	8	36	(135)
Corporate [Member]
Segment Reporting Information [Line Items]
Net income (loss)	$ (78)	$ (107)	$ (852)	$ (344)