CONSOLIDATED STATEMENTS OF OPERATIONS (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Net sales	$ 1,997.6	$ 1,593.8	$ 1,530.8	$ 1,383.5	$ 1,464.8	$ 1,331.3	$ 1,404.5	$ 1,369.8	$ 6,505.7	$ 5,570.4	$ 5,933.7
Cost of products sold (exclusive of items shown separately below)									6,007.7	5,107.8	5,539.1
Selling and administrative expenses (exclusive of items shown separately below)									247.2	205.3	208.7
Depreciation									201.9	190.1	192.0
Pension and OPEB expense (income) (exclusive of corridor charges shown below)									(92.5)	(68.6)	(35.3)
Pension corridor charges	2.0								2.0	0	157.3
Total operating costs									6,366.3	5,434.6	6,061.8
Operating profit (loss)	74.5	63.7	36.5	(35.3)	63.0	25.9	13.7	33.2	139.4	135.8	(128.1)
Interest expense									144.7	127.4	86.7
Other income (expense)									(21.1)	(1.4)	6.2
Income (loss) before income taxes									(26.4)	7.0	(208.6)
Income tax expense (benefit)									7.7	(10.4)	790.0
Net income (loss)									(34.1)	17.4	(998.6)
Less: Net income attributable to noncontrolling interests									62.8	64.2	28.7
Net income (loss) attributable to AK Steel Holding Corporation	$ 13.5	$ (7.2)	$ (17.1)	$ (86.1)	$ 35.2	$ (31.7)	$ (40.4)	$ (9.9)	$ (96.9)	$ (46.8)	$ (1,027.3)
Basic and diluted earnings per share:
Net income (loss) attributable to AK Steel Holding Corporation common stockholders (in dollars per share)					$ 0.26	$ (0.23)	$ (0.30)	$ (0.07)	$ (0.65)	$ (0.34)	$ (9.06)