Guarantees and Contingent Liabilities (Details) (USD $)	3 Months Ended
	Mar. 31, 2013 claim employee	Dec. 31, 2012
Guarantees:
Limitations or indemnifications of reinsurance agreements	$ 0
Proceedings:
Number of former employee agents plaintiffs seek benefits for	6,500
Number of claims asserted in Romero II	3
Number of claims barred in Romero II	2
Reserves for asbestos claims	1,000,000,000	1,030,000,000
Reinsurance recoverables for asbestos claims	486,000,000	496,000,000
Reserves for environmental claims	192,000,000	193,000,000
Reinsurance recoverables for environmental claims	48,000,000	48,000,000
Percentage of net asbestos and environmental reserves that were for incurred but not reported estimated losses	57.00%	58.00%
Minimum
Proceedings:
Loss contingencies, reasonably possible pretax loss exposure in excess of the amount accrued	0
Maximum
Proceedings:
Loss contingencies, reasonably possible pretax loss exposure in excess of the amount accrued	830,000,000
Guarantee on fixed income securities
Guarantees:
Maximum amount at risk pursuant to a guarantee	5,000,000
Residual guarantee
Guarantees:
Potential leased automobiles residual value	0
Maximum amount at risk pursuant to a guarantee	$ 44,000,000
Guarantee obligations term, low end of range	1 year
Guarantee obligations term, high end of range	3 years