Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2017	Oct. 27, 2017
Entity Registrant Name	American Railcar Industries, Inc.
Entity Central Index Key	0001344596
Document Type	10-Q
Document Period End Date	Sep. 30, 2017
Amendment Flag	false
Document Fiscal Year Focus	2017
Document Fiscal Period Focus	Q3
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Entity Common Stock, Shares Outstanding		19,083,878
Subsequent Event [Member]
Entity Common Stock, Shares Outstanding		19,083,878