Income Taxes (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Sep. 30, 2015
Income Taxes
Income tax expense reduction due to research and experimentation tax credit	$ 5,197	$ 5,063
Estimated decrease in liability for unrecognized tax benefits	3,385
Unrecognized tax benefits that, if recognized, would affect the effective tax rate	10,419		$ 10,494
Accrued interest and penalties	811		859
Unrecognized Tax Benefits	21,626		$ 21,469
Deferred Federal Income Tax Expense Benefit Related to Depreciation on Property, Plant and Equipment	$ 9,800