Schedule IV (SUPPLEMENTAL INFORMATION CONCERNING REINSURANCE) (Details) (USD $) In Millions, unless otherwise specified	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, 2014	Dec. 31, 2013	Dec. 31, 2012
Reinsurance Premiums for Insurance Companies, by Product Segment [Line Items]
Percentage of Amount Assumed to Net									19.00%	21.00%	21.00%
Net Amount	$ 4,370	$ 4,754	$ 4,332	$ 3,970	$ 4,363	$ 4,610	$ 4,067	$ 3,573	$ 17,426	$ 16,613	$ 15,677
Assumed From Other Companies									3,336	3,479	3,302
Ceded To Other Companies									5,465	5,722	5,427
Direct Amount									19,555	18,856	17,802
Property and Casualty [Member]
Reinsurance Premiums for Insurance Companies, by Product Segment [Line Items]
Percentage of Amount Assumed to Net									23.00%	25.00%	25.00%
Net Amount									12,767	12,141	11,265
Assumed From Other Companies									2,923	3,015	2,788
Ceded To Other Companies									4,940	5,160	4,918
Direct Amount									14,784	14,286	13,395
Accident and Health [Member]
Reinsurance Premiums for Insurance Companies, by Product Segment [Line Items]
Percentage of Amount Assumed to Net									4.00%	5.00%	5.00%
Net Amount									3,678	3,567	3,499
Assumed From Other Companies									141	168	190
Ceded To Other Companies									434	486	442
Direct Amount									3,971	3,885	3,751
Life [Member]
Reinsurance Premiums for Insurance Companies, by Product Segment [Line Items]
Percentage of Amount Assumed to Net									28.00%	33.00%	35.00%
Net Amount									981	905	913
Assumed From Other Companies									272	296	324
Ceded To Other Companies									91	76	67
Direct Amount									$ 800	$ 685	$ 656