Income Taxes (Details 2) (USD $)	12 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2012
Deferred tax assets attributable to:
Share-based compensation expense	$ 22,984,000	$ 20,668,000
Accrued liabilities	27,074,000	26,817,000
Inventory adjustments	2,450,000	3,771,000
Foreign loss carryforwards	31,882,000	28,776,000
Unrecognized tax benefits	370,000	437,000
Other	3,874,000	3,408,000
Total deferred tax assets	88,634,000	83,877,000
Valuation allowance	(29,926,000)	(26,073,000)
Total deferred tax assets, net	58,708,000	57,804,000
Deferred tax liabilities attributable to:
Depreciation and amortization	102,032,000	99,259,000
Total deferred tax liabilities	102,032,000	99,259,000
Net deferred tax liability	43,324,000	41,455,000
Domestic earnings before provision for income taxes	361,800,000	386,600,000	334,500,000
Foreign earnings before provision for income taxes	28,900,000	26,100,000	26,400,000
Accumulated undistributed earnings of the Company's foreign operations	202,900,000	170,900,000
Total operating loss carry-forward	103,000,000	96,400,000
Operating loss carry-forward, subject to valuation allowance	87,100,000	79,400,000
Amount of operating loss carry-forwards with an expiration date	25,400,000
Amount of operating loss carry-forwards without an expiration date	77,600,000
Tax credit carryforwards	$ 2,100,000	$ 2,000,000