CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) (unaudited) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Net income (loss)	$ 8.9	$ (15.7)	$ (63.8)	$ (34.4)
Other comprehensive income (loss), before tax:
Foreign currency translation gain (loss)	(2.5)	1.2	(2.6)	0.5
Cash flow hedges:
Gains (losses) arising in period	(2.7)	10.3	(9.6)	0.6
Reclassification of losses (gains) to net income (loss)	3.9	(5.9)	(0.1)	(20.5)
Unrealized holding gains (losses) on securities:
Unrealized holding gains (losses) arising in period	0	0	0	0.2
Pension and OPEB plans:
Prior service credit (cost) arising in period	(2.1)	(6.1)	(2.1)	(6.1)
Gains (losses) arising in period	(3.0)	9.6	(8.3)	9.6
Reclassification of prior service cost (credits) included in net income (loss)	(17.2)	(19.1)	(51.7)	(57.3)
Reclassification of losses (gains) included in net income (loss)	1.0	6.6	0.4	21.0
Other comprehensive income (loss), before tax	(22.6)	(3.4)	(74.0)	(52.0)
Income tax expense related to items of comprehensive income (loss)	0	0	0	0
Other comprehensive income (loss)	(22.6)	(3.4)	(74.0)	(52.0)
Comprehensive income (loss)	(13.7)	(19.1)	(137.8)	(86.4)
Less: Comprehensive income attributable to noncontrolling interests	16.1	16.0	46.6	47.6
Comprehensive income (loss) attributable to AK Steel Holding Corporation	$ (29.8)	$ (35.1)	$ (184.4)	$ (134.0)