CONSOLIDATED BALANCE SHEETS (USD $) In Millions, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Current Assets [Abstract]
Cash and cash equivalents	$ 210.3	$ 380.6
Accounts receivable, net	744.3	709.1
Total inventories, net	1,512.5	1,384.3
Deferred income taxes	0
Prepaid expenses and other current assets	60.4	95.5
Total Current Assets	2,527.5	2,569.5
Property, plant and equipment, net	2,444.0	2,368.8
Cost in excess of net assets acquired	737.7	737.7
Deferred income taxes	0	0
Other assets	370.8	370.9
Total Assets	6,080.0	6,046.9
Current Liabilities [Abstract]
Accounts payable	451.7	490.7
Accrued liabilities	327.9	320.3
Deferred income taxes	16.6	23.5
Debt Current	27.3	27.3
Total Current Liabilities	823.5	861.8
Long-term debt	1,474.1	1,482.0
Accrued postretirement benefits	473.3	488.1
Pension liabilities	496.1	508.9
Deferred income taxes	20.0	9.8
Other long-term liabilities	117.5	124.7
Total Liabilities	3,404.5	3,475.3
ATI Stockholders' Equity [Abstract]
Preferred stock, par value $0.10: authorized-50,000,000 shares; issued-none	0	0
Common stock	11.0	11.0
Additional paid-in capital	1,169.7	1,207.1
Retained earnings	2,429.8	2,361.5
Treasury stock	(122.6)	(162.7)
Accumulated other comprehensive loss, net of tax	(912.4)	(941.6)
Total ATI stockholders' equity	2,575.5	2,475.3
Noncontrolling interests
Noncontrolling interests	100.0	96.3
Total Stockholders' Equity	2,675.5	2,571.6
Total Liabilities and Equity	$ 6,080.0	$ 6,046.9