v3.26.1
Document And Entity Information - shares
3 Months Ended
Mar. 31, 2026
May 01, 2026
Document Information Line Items    
Entity Central Index Key 0001461237  
Document Type 10-Q  
Document Quarterly Report true  
Document Period End Date Mar. 31, 2026  
Document Fiscal Year Focus 2026  
Document Transition Report false  
Entity File Number 0-53967  
Entity Registrant Name GRAHAM ALTERNATIVE INVESTMENT FUND II LLC  
Entity Incorporation, State or Country Code DE  
Entity Tax Identification Number 20-4897149  
Entity Address, Address Line One 40 Highland Avenue  
Entity Address, City or Town Rowayton  
Entity Address, State or Province CT  
Entity Address, Postal Zip Code 06853  
City Area Code 203  
Local Phone Number 899-3400  
Entity Current Reporting Status Yes  
Entity Interactive Data Current Yes  
Entity Filer Category Non-accelerated Filer  
Entity Small Business true  
Entity Emerging Growth Company false  
Entity Shell Company false  
Entity Common Stock, Shares Outstanding   158,848.391
Amendment Flag false  
Document Fiscal Period Focus Q1  
Current Fiscal Year End Date --12-31