Taxation (Components Of Net Deferred Tax Assets) (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Deferred Tax Assets, Gross [Abstract]
Loss reserve discount	$ 1,269	$ 663
Unearned premium reserve	498	190
Foreign tax credits	2,115	969
Provision for uncollectible balances	72	65
Loss carry-forwards	92	72
Debt related amounts	219	3
Compensation related amounts	449	189
Cumulative translation adjustments	59	17
Other, net	69	80
Total deferred tax assets	4,842	2,248
Deferred Tax Liabilities, Gross [Abstract]
Deferred policy acquisition costs	842	412
VOBA and other intangible assets	2,352	384
Un-remitted foreign earnings	2,001	827
Investments	406	6
Unrealized appreciation on investments	60	195
Depreciation	91	68
Deferred Tax Liabilities, Gross	5,752	1,892
Valuation allowance	78	38
Deferred Income Tax Assets, Net	0	$ 318
Deferred Tax Liabilities, Net	$ (988)