Cover - USD ($)	12 Months Ended
	Dec. 31, 2025	Mar. 03, 2026	Jun. 30, 2025
Document Information [Line Items]
Document Type	10-K
Document Annual Report	true
Document Transition Report	false
Document Financial Statement Error Correction [Flag]	false
Entity Interactive Data Current	Yes
ICFR Auditor Attestation Flag	false
Amendment Flag	false
Document Period End Date	Dec. 31, 2025
Document Fiscal Year Focus	2025
Document Fiscal Period Focus	FY
Documents Incorporated by Reference [Text Block]	None.
Entity Information [Line Items]
Entity Registrant Name	ISQ Open Infrastructure Company LLC
Entity Central Index Key	0002059924
Entity File Number	000-56735
Entity Tax Identification Number	33-2876284
Entity Incorporation, State or Country Code	DE
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Shell Company	false
Entity Filer Category	Non-accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
Entity Public Float			$ 0
Entity Contact Personnel [Line Items]
Entity Address, Address Line One	600 Brickell Avenue
Entity Address, Address Line Two	PH
Entity Address, City or Town	Miami
Entity Address, State or Province	FL
Entity Address, Postal Zip Code	33131
Entity Phone Fax Numbers [Line Items]
City Area Code	(786)
Local Phone Number	693-5700
ISQ Open Infrastructure Company LLC - Series I | Class F-STE Shares
Entity Listings [Line Items]
Entity Common Stock, Shares Outstanding		337,317
ISQ Open Infrastructure Company LLC - Series I | Class F-DTE Shares
Entity Listings [Line Items]
Entity Common Stock, Shares Outstanding		401,563
ISQ Open Infrastructure Company LLC - Series I | Class F-ITE Shares
Entity Listings [Line Items]
Entity Common Stock, Shares Outstanding		54,970
ISQ Open Infrastructure Company LLC - Series I | Class F-JTE Shares
Entity Listings [Line Items]
Entity Common Stock, Shares Outstanding		663,483
ISQ Open Infrastructure Company LLC - Series I | Class STE Shares
Entity Listings [Line Items]
Entity Common Stock, Shares Outstanding		110
ISQ Open Infrastructure Company LLC - Series I | Class DTE Shares
Entity Listings [Line Items]
Entity Common Stock, Shares Outstanding		110
ISQ Open Infrastructure Company LLC - Series I | Class ITE Shares
Entity Listings [Line Items]
Entity Common Stock, Shares Outstanding		110
ISQ Open Infrastructure Company LLC - Series I | Class JTE Shares
Entity Listings [Line Items]
Entity Common Stock, Shares Outstanding		110
ISQ Open Infrastructure Company LLC - Series I | Class ETE Shares
Entity Listings [Line Items]
Entity Common Stock, Shares Outstanding		80
ISQ Open Infrastructure Company LLC - Series II | Class F-S Shares
Entity Listings [Line Items]
Entity Common Stock, Shares Outstanding		627,403
ISQ Open Infrastructure Company LLC - Series II | Class F-I Shares
Entity Listings [Line Items]
Entity Common Stock, Shares Outstanding		276,098
ISQ Open Infrastructure Company LLC - Series II | Class F-J Shares
Entity Listings [Line Items]
Entity Common Stock, Shares Outstanding		3,634,961
ISQ Open Infrastructure Company LLC - Series II | Class E Shares
Entity Listings [Line Items]
Entity Common Stock, Shares Outstanding		412,345