Document and Entity Information - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Feb. 19, 2016	Jun. 30, 2015
Entity Information [Line Items]
Entity Registrant Name	American Railcar Industries, Inc.
Entity Central Index Key	0001344596
Document Type	10-K
Document Period End Date	Dec. 31, 2015
Amendment Flag	false
Entity Common Stock, Shares Outstanding		19,683,446
Document Fiscal Year Focus	2015
Document Fiscal Period Focus	FY
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Entity Well-known Seasoned Issuer	No
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Public Float			$ 460
Subsequent Event [Member]
Entity Information [Line Items]
Entity Common Stock, Shares Outstanding		19,683,446