Income Taxes (Schedule Of Effective Income Tax Rate Reconciliation) (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Income Tax Disclosure [Abstract]
Current income tax expense (benefit)	$ 85	$ (6)	$ 72	$ (87)
Deferred income tax expense (benefit)	86	(1,708)	(300)	(5,348)
Total income tax expense (benefit)	$ 171	$ (1,714)	$ (228)	$ (5,435)
U.S. statutory income tax rate	35.00%	35.00%	35.00%	35.00%
Deferred tax asset valuation allowance	(35.00%)	0.00%	(20.00%)	0.00%
Non-deductible goodwill and intangible impairment	6.00%	(5.00%)	(9.00%)	(2.00%)
Change in unrecognized tax benefits	7.00%	0.00%	(2.00%)	0.00%
Taxation on Canadian operations	0.00%	0.00%	(3.00%)	(1.00%)
State income taxes	2.00%	1.00%	1.00%	2.00%
Other	0.00%	(1.00%)	3.00%	1.00%
Effective income tax rate	15.00%	30.00%	5.00%	35.00%

Amount of current income tax expense (benefit) pertaining to taxable income (loss) from continuing operations.

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