Goodwill And Identifiable Intangible Assets (Narrative) (Details) - USD ($)		3 Months Ended			9 Months Ended
		Sep. 30, 2015	Mar. 31, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 01, 2014
Goodwill [Line Items]
Business Acquisition, Goodwill, Expected Tax Deductible Amount		$ 0			$ 0
Impairment of goodwill (Note 3)		700,000,000	$ 700,000,000	$ 0	$ 1,400,000,000	$ 0
Goodwill, Period Increase (Decrease)		$ 700,000,000				0
Reporting Unit, Percentage of Fair Value in Excess of Carrying Amount			34.00%				17.00%
Discount rate Applied to Internally Developed Cash Flow Projections		6.00%	6.00%		6.00%		6.25%
Amortization of Intangible Assets	[1]	$ 30,000,000		40,000,000	$ 79,000,000	118,000,000
Environmental allowances and credits [Member]
Goodwill [Line Items]
Impairment of Intangible Assets (Excluding Goodwill)		4,000,000		0	55,000,000	0
Mine Development [Member]
Goodwill [Line Items]
Impairment of Intangible Assets (Excluding Goodwill)		19,000,000		0	19,000,000	0
Favorable purchase and sales contracts [Member]
Goodwill [Line Items]
Impairment of Intangible Assets (Excluding Goodwill)		0		0	8,000,000	0
Depreciation and amortization [Member]
Goodwill [Line Items]
Amortization of Intangible Assets		$ 24,000,000		$ 29,000,000	$ 64,000,000	$ 87,000,000

[1] Amounts recorded in depreciation and amortization totaled $24 million and $29 million for the three months ended September 30, 2015 and 2014, respectively, and $64 million and $87 million for the nine months ended September 30, 2015 and 2014, respectively.