Income Taxes (Schedule Of Effective Income Tax Rate Reconciliation) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016		Dec. 31, 2015
Income Tax Disclosure [Abstract]
Total income tax expense (benefit)	$ (182)	$ 141	[1]	$ (6,213)	[1]
U.S. statutory income tax rate	35.00%	35.00%		35.00%
Non-deductible goodwill and intangible impairment	0.00%	(23.00%)		(3.00%)
U.S. Tax Reform	8.00%	0.00%		0.00%
Legal entity restructuring	(81.00%)	6.00%		0.00%
Other	(13.00%)	0.00%		1.00%
Deferred tax asset valuation allowance	31.00%	(29.00%)		(2.00%)
Effective income tax rate	(20.00%)	(11.00%)		31.00%

[1] Prior year amounts have been recast due to change in accounting principle. See Note 2 in “Item 8. Financial Statements and Supplementary Data” of this report.