Document and Entity Information Document - USD ($)	12 Months Ended
	Dec. 31, 2019	Feb. 18, 2020	Jun. 30, 2019
Entity Information [Line Items]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2019
Document Transition Report	false
Entity File Number	1-13696
Entity Registrant Name	AK STEEL HOLDING CORPORATION
Amendment Flag	false
Entity Central Index Key	0000918160
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	FY
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	31-1401455
Entity Address, Address Line One	9227 Centre Pointe Drive
Entity Address, City or Town	West Chester
Entity Address, State or Province	OH
Entity Address, Postal Zip Code	45069
City Area Code	(513)
Local Phone Number	425-5000
Title of 12(b) Security	Common Stock $0.01 Par Value
Trading Symbol	AKS
Security Exchange Name	NYSE
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Public Float			$ 743,645,887
Entity Common Stock, Shares Outstanding		316,909,268
Documents Incorporated by Reference [Text Block]	The information required to be furnished pursuant to Part III of this Form 10-K will be set forth in, and incorporated by reference from, the registrant’s definitive proxy statement for the annual meeting of stockholders (the “2020 Proxy Statement”), which will be filed with the Securities and Exchange Commission not later than 120 days after the end of the fiscal year ended December 31, 2019.