Income Taxes (Exp) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Components of provision (benefit) for income taxes
Current tax expense	$ 39	$ 254	$ 286
Deferred tax expense (benefit)	68	(134)	(194)
Income tax expense	$ 107	$ 120	$ 92
Reconciliation of the differences between the income tax expense for the entity's continuing operations computed at the Swiss holding company statutory rate and the reported provision for income taxes
Annual effective tax rate (as a percent)	11.50%	11.90%	(5.00%)
Income tax expense, calculated at the Swiss federal statutory rate of 7.83 percent	$ 72	$ 80	$ (141)
Swiss holding company federal statutory rate (as a percent)	7.83%
Taxes on earnings subject to rates different than the Swiss federal statutory rate	$ 34	36	91
Taxes on impairment losses subject to rates different than the Swiss federal statutory rate	5	(8)	174
Taxes on revaluation of Norwegian assets	18	14	5
Taxes on litigation matters subject to rates different than the Swiss federal statutory rate	(1)	(9)	5
Changes in unrecognized tax benefits, net	(31)	12	(112)
Change in valuation allowance	32	10	93
Benefit from foreign tax credits	(16)	(10)	(23)
Other, net	(6)	(5)
Income tax expense	$ 107	$ 120	$ 92