Schedule IV (SUPPLEMENTAL INFORMATION CONCERNING REINSURANCE) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Reinsurance Premiums for Insurance Companies, by Product Segment [Line Items]
Percentage of Amount Assumed to Net									21.00%	19.00%	21.00%
Net Amount	$ 4,207	$ 4,719	$ 4,360	$ 3,927	$ 4,370	$ 4,754	$ 4,332	$ 3,970	$ 17,213	$ 17,426	$ 16,613
Assumed From Other Companies									3,676	3,336	3,479
Ceded To Other Companies									5,818	5,465	5,722
Direct Amount									$ 19,355	$ 19,555	$ 18,856
Property and Casualty [Member]
Reinsurance Premiums for Insurance Companies, by Product Segment [Line Items]
Percentage of Amount Assumed to Net									25.00%	23.00%	25.00%
Net Amount									$ 12,781	$ 12,767	$ 12,141
Assumed From Other Companies									3,259	2,923	3,015
Ceded To Other Companies									5,373	4,940	5,160
Direct Amount									$ 14,895	$ 14,784	$ 14,286
Accident and Health [Member]
Reinsurance Premiums for Insurance Companies, by Product Segment [Line Items]
Percentage of Amount Assumed to Net									5.00%	4.00%	5.00%
Net Amount									$ 3,501	$ 3,678	$ 3,567
Assumed From Other Companies									168	141	168
Ceded To Other Companies									351	434	486
Direct Amount									$ 3,684	$ 3,971	$ 3,885
Life [Member]
Reinsurance Premiums for Insurance Companies, by Product Segment [Line Items]
Percentage of Amount Assumed to Net									27.00%	28.00%	33.00%
Net Amount									$ 931	$ 981	$ 905
Assumed From Other Companies									249	272	296
Ceded To Other Companies									94	91	76
Direct Amount									$ 776	$ 800	$ 685