Taxation (Components Of Net Deferred Tax Assets) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Deferred Tax Assets, Gross [Abstract]
Loss reserve discount	$ 849	$ 933
Unearned premium reserve	98	85
Foreign tax credits	1,131	1,074
Investments	43	67
Provision for uncollectible balances	110	113
Loss carry-forwards	55	43
Other, net	110	31
Cumulative translation adjustment	0	5
Total deferred tax assets	2,396	2,351
Deferred Tax Liabilities, Gross [Abstract]
Deferred policy acquisition costs	68	47
VOBA and other intangible assets	379	372
Un-remitted foreign earnings	795	810
Unrealized appreciation on investments	586	392
Deferred Tax Liabilities, Unrealized Currency Transaction Gains	59	0
Total deferred tax liabilities	1,887	1,621
Valuation allowance	56	57
Net deferred tax assets	$ 453	$ 673