Segments Information (Details 1) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Income (loss) before income tax [Abstract]
Insurance underwriting income	$ 475	$ 1,162	$ 1,584
Reinsurance assumed underwriting income	36	30	74
Underwriting income before deferred policy acquisition costs	511	1,192	1,658
Increase (decrease) in deferred policy acquisition costs	63	30	(27)
Underwriting income	574	1,222	1,631
Investment income	1,605	1,630	1,610
Total property and casualty insurance	2,157	2,782	3,177
Corporate and other loss	(246)	(220)	(238)
Realized investment gains, Net	288	426	23
INCOME BEFORE FEDERAL AND FOREIGN INCOME TAX	2,199	2,988	2,962
Assets [Abstract]
Total assets	50,865	50,249	50,449
Personal insurance [Member]
Income (loss) before income tax [Abstract]
Insurance underwriting income	47	303	600
Commercial insurance [Member]
Income (loss) before income tax [Abstract]
Insurance underwriting income	1	347	510
Specialty insurance [Member]
Income (loss) before income tax [Abstract]
Insurance underwriting income	427	512	474
Adjustments and eliminations [Member]
Assets [Abstract]
Total assets	(83)	(72)	(109)
Corporate and other [Member]
Assets [Abstract]
Total assets	2,513	2,483	2,876
Property and casualty insurance [Member]
Income (loss) before income tax [Abstract]
Investment income	1,562	1,558	1,549
Other income (charges)	21	2	(3)
Assets [Abstract]
Total assets	$ 48,435	$ 47,838	$ 47,682