Earnings Per Share (Tables)

9 Months Ended

Sep. 30, 2012

Earnings Per Share [Abstract]

Earnings per share

	Three Months Ended September 30,						Nine Months Ended September 30,
	2012			2011			2012			2011
Net income (loss) attributable to AK Steel Holding Corporation	$	(60.9	)	$	(3.5	)	$	(796.9	)	$	38.3
Less: distributed earnings to common stockholders and holders of certain stock compensation awards	—			5.5			11.0			16.5
Undistributed earnings (loss)	$	(60.9	)	$	(9.0	)	$	(807.9	)	$	21.8
Common stockholders earnings—basic and diluted:
Distributed earnings to common stockholders	$	—		$	5.5		$	11.0		$	16.5
Undistributed earnings (loss) to common stockholders	(60.6		)	(9.1		)	(804.9		)	21.6
Common stockholders earnings (loss)—basic and diluted	$	(60.6	)	$	(3.6	)	$	(793.9	)	$	38.1
Common shares outstanding (weighted-average shares in millions):
Common shares outstanding for basic earnings per share	110.2			109.8			110.1			109.8
Effect of dilutive stock-based compensation	—			—			—			0.1
Common shares outstanding for diluted earnings per share	110.2			109.8			110.1			109.9
Basic and diluted earnings per share:
Distributed earnings	$	—		$	0.05		$	0.10		$	0.15
Undistributed earnings (loss)	(0.55		)	(0.08		)	(7.31		)	0.20
Basic and diluted earnings (loss) per share	$	(0.55	)	$	(0.03	)	$	(7.21	)	$	0.35
Potentially issuable common shares (in millions) excluded from earnings per share calculation due to anti-dilutive effect	2.0			1.1			2.0			0.9