CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Other comprehensive income (loss), before tax:
Foreign currency translation gain (loss)	$ 0.7	$ (1.5)	$ 0.3	$ 0
Cash flow hedges:
Gains (losses) arising in period	(8.5)	(4.6)	(21.2)	(5.0)
Reclassification of losses (gains) to net income (loss)	11.3	(1.9)	31.9	3.4
Unrealized holding gains (losses) on securities:
Unrealized holding gains (losses) arising in period	0.5	(1.3)	0.8	(1.0)
Pension and OPEB plans:
Prior service cost arising in period	0	0	0	(29.6)
Reclassification of prior service cost (credits) included in net income (loss)	(18.3)	(18.0)	(55.0)	(40.1)
Gains (losses) arising in period	0	0	0	(4.3)
Reclassification of losses (gains) included in net income (loss)	6.1	4.4	18.3	(0.7)
Other comprehensive income (loss), before tax	(8.2)	(22.9)	(24.9)	(77.3)
Income tax provision (benefit) related to items of comprehensive income (loss)	0	(8.0)	0	(29.2)
Other comprehensive income (loss)	(8.2)	(14.9)	(24.9)	(48.1)
Net income (loss)	(52.5)	(6.1)	(777.0)	34.8
Comprehensive income (loss)	(60.7)	(21.0)	(801.9)	(13.3)
Less: Comprehensive income (loss) attributable to noncontrolling interests	8.4	(2.6)	19.9	(3.5)
Comprehensive income (loss) attributable to AK Steel Holding Corporation	$ (69.1)	$ (18.4)	$ (821.8)	$ (9.8)