Document and Entity Information (USD $) In Millions, except Share data	9 Months Ended
	Jun. 30, 2011	Jul. 29, 2011	Mar. 31, 2010
Document and Entity Information [Abstract]
Entity Registrant Name	AMERICAN PACIFIC CORP
Entity Central Index Key	0000350832
Document Type	10-Q
Document Period End Date	Jun. 30, 2011
Amendment Flag	false
Document Fiscal Year Focus	2011
Document Fiscal Period Focus	Q3
Current Fiscal Year End Date	--09-30
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Smaller Reporting Company
Entity Public Float			$ 47.2
Entity Common Stock, Shares Outstanding		7,559,591