Investments (Schedule Of Investments In Partially-Owned Insurance Companies) (Details) (USD $) In Millions, unless otherwise specified							12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2012 Freisenbruch-Meyer Bermuda	Dec. 31, 2011 Freisenbruch-Meyer Bermuda	Dec. 31, 2012 ACE Cooperative Ins. Co. - Saudi Arabia Saudi Arabia	Dec. 31, 2011 ACE Cooperative Ins. Co. - Saudi Arabia Saudi Arabia	Dec. 31, 2012 Huatai Group	Dec. 31, 2012 Huatai Group China	Dec. 31, 2011 Huatai Group China	Dec. 31, 2012 Huatai Life Insurance Company China	Dec. 31, 2011 Huatai Life Insurance Company China	Dec. 31, 2012 Russian Reinsurance Company Russia	Dec. 31, 2011 Russian Reinsurance Company Russia	Dec. 31, 2012 Island Heritage Cayman Islands	Dec. 31, 2011 Island Heritage Cayman Islands
Investment [Line Items]
Carrying Value	$ 454	$ 352	$ 9	$ 8	$ 9	$ 7		$ 350	$ 228	$ 84	$ 103	$ 2	$ 2	$ 0	$ 4
Issued Share Capital	716	716	6	5	27	27		474	457	205	196	4	4	0	27
Ownership Percentage			40.00%	40.00%	30.00%	30.00%		20.00%	20.00%	20.00%	20.00%	23.30%	23.30%	0.00%	10.80%
Additional investment pending regulatory approval							$ 100