Taxation (Reconciliation Of The Difference Between The Provision for Income Taxes and the Expected Tax Provision at Swiss Statutory Income Tax Rate) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Expected tax provision at Swiss statutory rate		$ 388	$ 258	$ 273
Taxes on earnings subject to rates other that Swiss statutory rate		582	193	224
Income Tax Reconciliation, Change To Deferred Taxes Related To Unrealized Foreign Exchange	[1]	0	0	139
Tax exempt interest and dividends received deduction, net of proration		(200)	(32)	(33)
Net witholding taxes		20	35	33
Change in valuation allowance		(1)	2	(20)
Other		26	6	18
Provision for income taxes		$ 815	$ 462	$ 634

[1] (1) 2014 includes a charge to deferred taxes related to non-recognition of foreign tax credits related to unrealized foreign exchange losses.