FINANCING ARRANGEMENTS: (Details) - USD ($)	3 Months Ended		12 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Jun. 30, 2015	Jul. 31, 2014	Nov. 30, 2013
Long-term debt
Net carrying amount of long-term debt	$ 120,000,000		$ 120,002,000
Less current portion	0		(2,000)
Long-term debt	$ 120,000,000		120,000,000
Convertible senior notes
Long-term debt
Interest rate percentage	5.00%	5.00%		5.00%
Net carrying amount of long-term debt	$ 0		0
Long-term debt, additional disclosures
Face amount of debt				$ 172,500,000
Interest expense related to contractual interest coupon		$ 400,000
Interest cost related to amortization of the discount		$ 300,000
Senior term notes
Long-term debt
Interest rate percentage	5.75%				5.75%
Net carrying amount of long-term debt	$ 120,000,000		120,000,000
Long-term debt, additional disclosures
Face amount of debt					$ 120,000,000
Revolving credit facility
Long-term debt
Net carrying amount of long-term debt	0		0
Revolving Credit Facility
Line of Credit Facility, Amount Outstanding	0		0
Outstanding standby letters of credit	2,100,000
Revolving credit facility remaining borrowing capacity	$ 397,900,000		$ 397,900,000
Equipment and leasehold notes payable
Long-term debt
Interest rate percentage, minimum	4.90%		4.90%
Interest rate percentage, maximum	8.75%		8.75%
Net carrying amount of long-term debt	$ 0		$ 2,000