Document and Entity Information	3 Months Ended
	Dec. 31, 2011	Jan. 31, 2011
Document and Entity Information [Abstract]
Entity Registrant Name	AMERICAN PACIFIC CORP
Entity Central Index Key	0000350832
Document Type	10-Q
Document Period End Date	Dec. 31, 2011
Amendment Flag	false
Document Fiscal Year Focus	2012
Document Fiscal Period Focus	Q1
Current Fiscal Year End Date	--09-30
Entity Filer Category	Smaller Reporting Company
Entity Common Stock, Shares Outstanding		7,612,091