Earnings Per Share (Tables)

6 Months Ended

Jun. 30, 2014

Earnings Per Share [Abstract]

Earnings per share

	Three Months Ended June 30,						Six Months Ended June 30,
	2014			2013			2014			2013
Net income (loss) attributable to AK Steel Holding Corporation	$	(17.1	)	$	(40.4	)	$	(103.2	)	$	(50.3	)
Less: distributed earnings to common stockholders and holders of certain stock compensation awards	—			—			—			—
Undistributed earnings (loss)	$	(17.1	)	$	(40.4	)	$	(103.2	)	$	(50.3	)
Common stockholders earnings—basic and diluted:
Distributed earnings to common stockholders	$	—		$	—		$	—		$	—
Undistributed earnings (loss) to common stockholders	(17.0		)	(40.3		)	(102.8		)	(50.1		)
Common stockholders earnings (loss)—basic and diluted	$	(17.0	)	$	(40.3	)	$	(102.8	)	$	(50.1	)
Common shares outstanding (weighted-average shares in millions):
Common shares outstanding for basic earnings per share	136.2			135.8			136.2			135.8
Effect of exchangeable debt	—			—			—			—
Effect of dilutive stock-based compensation	—			—			—			—
Common shares outstanding for diluted earnings per share	136.2			135.8			136.2			135.8
Basic and diluted earnings per share:
Distributed earnings	$	—		$	—		$	—		$	—
Undistributed earnings (loss)	(0.13		)	(0.30		)	(0.76		)	(0.37		)
Basic and diluted earnings (loss) per share	$	(0.13	)	$	(0.30	)	$	(0.76	)	$	(0.37	)
Potentially issuable common shares (in millions) excluded from earnings per share calculation due to anti-dilutive effect	8.3			2.5			8.2			2.5