Restructuring And Other Charges (Narrative) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended			6 Months Ended		12 Months Ended		3 Months Ended		6 Months Ended		3 Months Ended	6 Months Ended		12 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended	12 Months Ended		6 Months Ended	3 Months Ended	6 Months Ended	3 Months Ended		6 Months Ended		3 Months Ended	12 Months Ended	3 Months Ended	12 Months Ended	3 Months Ended		6 Months Ended		12 Months Ended	3 Months Ended	6 Months Ended	3 Months Ended				6 Months Ended	3 Months Ended	6 Months Ended	3 Months Ended		6 Months Ended	3 Months Ended		6 Months Ended	3 Months Ended		6 Months Ended				3 Months Ended	6 Months Ended	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Mar. 31, 2010	Jun. 30, 2011	Jun. 30, 2010	Dec. 31, 2010	Dec. 31, 2009	Jun. 30, 2011 Foreign Currency Movements [Member]	Jun. 30, 2010 Foreign Currency Movements [Member]	Jun. 30, 2011 Foreign Currency Movements [Member]	Jun. 30, 2010 Foreign Currency Movements [Member]	Jun. 30, 2010 Other Exit Costs [Member]	Jun. 30, 2011 Other Exit Costs [Member]	Jun. 30, 2010 Other Exit Costs [Member]	Dec. 31, 2010 Other Exit Costs [Member]	Jun. 30, 2011 Restructuring Programs, 2011 [Member]	Jun. 30, 2011 Litigation Matter [Member]	Jun. 30, 2011 Litigation Matter [Member]	Dec. 31, 2009 Restructuring Programs, 2009 [Member]	Dec. 31, 2010 Restructuring Programs, 2010 [Member]	Jun. 30, 2010 Asset Impairments [Member]	Jun. 30, 2011 Other Restructuring Charges [Member]	Jun. 30, 2011 Other Restructuring Charges [Member]	Jun. 30, 2011 Reversal of Prior Periods' Layoff Reserves [Member]	Jun. 30, 2010 Reversal of Prior Periods' Layoff Reserves [Member]	Jun. 30, 2011 Reversal of Prior Periods' Layoff Reserves [Member]	Jun. 30, 2010 Reversal of Prior Periods' Layoff Reserves [Member]	Mar. 31, 2010 Asset Retirement Obligations [Member]	Dec. 31, 2010 Asset Retirement Obligations [Member]	Mar. 31, 2010 Environmental Remediation [Member]	Dec. 31, 2010 Environmental Remediation [Member]	Jun. 30, 2011 Layoff Costs [Member]	Jun. 30, 2010 Layoff Costs [Member]	Jun. 30, 2011 Layoff Costs [Member]	Jun. 30, 2010 Layoff Costs [Member]	Dec. 31, 2010 Layoff Costs [Member]	Mar. 31, 2010 Permanent Shutdown and Planned Demolition of Idled Structures [Member]	Jun. 30, 2010 Permanent Shutdown and Planned Demolition of Idled Structures [Member]	Mar. 31, 2010 Permanent Shutdown and Planned Demolition of Idled Structures [Member] Frederick, MD [Member] MT	Mar. 31, 2010 Permanent Shutdown and Planned Demolition of Idled Structures [Member] Badin, NC [Member] MT	Mar. 31, 2010 Permanent Shutdown and Planned Demolition of Idled Structures [Member] Comfort, TX [Member] MT	Jun. 30, 2011 Restructuring Programs (Layoffs), 2011 [Member]	Jun. 30, 2011 Restructuring Programs (Layoffs), 2011 [Member]	Jun. 30, 2011 Restructuring Programs (Layoffs), 2010 [Member]	Jun. 30, 2011 Restructuring Programs (Layoffs), 2010 [Member]	Jun. 30, 2011 Restructuring Programs (Layoffs), 2009 [Member]	Mar. 31, 2011 Restructuring Programs (Layoffs), 2009 [Member]	Jun. 30, 2011 Alumina [Member]	Jun. 30, 2011 Alumina [Member]	Jun. 30, 2010 Alumina [Member]	Jun. 30, 2010 Alumina [Member]	Jun. 30, 2011 Engineered Products and Solutions [Member]	Jun. 30, 2010 Engineered Products and Solutions [Member]	Jun. 30, 2011 Engineered Products and Solutions [Member]	Jun. 30, 2010 Engineered Products and Solutions [Member]	Jun. 30, 2011 Flat-Rolled Products [Member]	Jun. 30, 2010 Flat-Rolled Products [Member]	Jun. 30, 2010 Corporate [Member]	Jun. 30, 2010 Corporate [Member]	Jun. 30, 2011 Primary Metals [Member]	Jun. 30, 2010 Primary Metals [Member]	Jun. 30, 2011 Primary Metals [Member]	Jun. 30, 2010 Primary Metals [Member]
Restructuring and other charges	$ 34	$ 30		$ 40	$ 217			$ 6	$ 8	$ 8	$ 15	$ 1		$ 7			$ 20	$ 20			$ 128	$ 2	$ 3	$ 2	$ 7	$ 4	$ 15					$ 8	$ 28	$ 13	$ 36
Restructuring and other charges, after tax and noncontrolling interests	16	20		21	139			4	5	5	10	1		5			8	8			81	2	3	2			3		30		14		19	8	24
Number of employees associated with layoff costs	120	600		480	800																																											30	20	10	10	30	460	30	625	350	25	70	80	70	60	70	60
Other asset impairment charges																																					128
Other exit costs																												30		14							46	46
Other exit costs, after tax and noncontrolling interests																												19		9								29
Other restructuring activities																																					2
Other restructuring activities, after tax and noncontrolling interests																																					1
Cash payments				20		108							4		15																			16		93						2	3	1	4	4	9
Reduction in production - result of market conditions, in kmt																																							195.000	60.000
Asset impairments			1
Expansion of production plan included in asset impairment, kmt																																									40.000
Estimated decrease in number of employees due to restructuring				480		880	6,000									50			5,600	740
Inventory write-down - permanent shutdown and planned demolition of idled structures																																					8
Inventory write-down, after tax and non-controlling interests																																					5
Minimum amount of cash payments expected to be paid beyond the end of the current annual period				55
Maximum amount of cash payments expected to be paid beyond the end of the current annual period				$ 60