Taxation (Components Of Net Deferred Tax Assets) (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Deferred Tax Assets, Gross [Abstract]
Loss reserve discount	$ 884	$ 826
Unearned premium reserve	496	519
Foreign tax credits	222	247
Provision for uncollectible balances	46	37
Loss carry-forwards	123	143
Debt related amounts	69	74
Compensation related amounts	281	261
Cumulative translation adjustments	120	33
Unrealized depreciation on investments	75	0
Deferred Tax Asset, Lease Liability	121	140
Total deferred tax assets	2,437	2,280
Deferred Tax Liabilities, Gross [Abstract]
Deferred policy acquisition costs	522	588
VOBA and other intangible assets	1,425	1,468
Un-remitted foreign earnings	77	73
Investments	0	40
Unrealized appreciation on investments	957	470
Depreciation	123	157
Leasing Arrangements	111	129
Deferred Tax Liabilities, Other	31	45
Deferred Tax Liabilities, Gross	3,246	2,970
Valuation allowance	83	114
Deferred Tax Liabilities, Net	$ (892)	$ (804)