Document and Entity Information	9 Months Ended
	Sep. 30, 2021 shares
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2021
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q3
Document Transition Report	false
Entity File Number	0-53967
Entity Registrant Name	GRAHAM ALTERNATIVE INVESTMENT FUND II LLC
Entity Central Index Key	0001461237
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	183,776.720