Document And Entity Information	6 Months Ended
	Dec. 31, 2011	Jan. 24, 2012
Entity Registrant Name	ASPEN TECHNOLOGY INC /DE/
Entity Central Index Key	0000929940
Current Fiscal Year End Date	--06-30
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		93,703,317
Document Fiscal Year Focus	2012
Document Fiscal Period Focus	Q2
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Dec. 31, 2011