Document And Entity Information - USD ($)	12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Aggregate Market Value of Non-affiliates	$ 44,668,200
Capital Units, Outstanding	13,327	13,327
Entity Registrant Name	Southwest Iowa Renewable Energy, LLC
Entity Central Index Key	0001424844
Current Fiscal Year End Date	--09-30
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Shell Company	false
Entity Address, Address Line One	10868 189th street
Entity Address, City or Town	Council Bluffs
Entity Address, State or Province	IA
Entity Address, Postal Zip Code	51503
City Area Code	712
Local Phone Number	366-0392
Entity Tax Identification Number	20-2735046
Entity File Number	000-53041
Document Type	10-K
Entity Emerging Growth Company	false
Document Period End Date	Sep. 30, 2019
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	FY
Amendment Flag	false
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Incorporation, State or Country Code	IA
Document Annual Report	true
Document Transition Report	false
Entity Public Float	$ 52,134,000
Common Class A [Member]
Entity Common Stock, Shares Outstanding	8,810
Common Class B [Member]
Entity Common Stock, Shares Outstanding	3,334
Common Class C [Member]
Entity Common Stock, Shares Outstanding	1,000