Stock-Based Compensation Plans (Details 5) (USD $)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2011 Stock Option [Member]	Dec. 31, 2010 Stock Option [Member]
Summary of stock option activities
Options exercisable		3,593,863	2,889,066
Number of options, Beginning Balance	2,889,066
Weighted Average Exercise Price, Beginning Balance	$ 35.18
Options granted	662,122
Weighted Average Exercise Price of Options granted	$ 37.75
Converted Allegheny options	1,805,811
Converted Allegheny options, Weighted Average Exercise Price	$ 41.75
Options exercised	(973,817)
Weighted Average Exercise Price of Options exercised	$ 31.48
Options forfeited/expired	(127,197)
Weighted Average Exercise Price of forfeited/expired	$ 70.19
Number of options, Ending Balance	4,255,985
Weighted Average Exercise Price, Ending Balance	$ 38.17