Document And Entity Information	3 Months Ended
	Dec. 31, 2011	Jan. 31, 2011
Document And Entity Information [Abstract]
Entity Registrant Name	ATWOOD OCEANICS INC
Entity Central Index Key	0000008411
Current Fiscal Year End Date	--09-30
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		65,181,034
Document Fiscal Year Focus	2012
Document Fiscal Period Focus	Q1
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Dec. 31, 2011
Trading Symbol	atw