Shareholders' Equity - AOCI Reclassifications (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Accumulated other comprehensive income (loss) components which were reclassified to the Consolidated Statement of Operations
Income tax provision	$ 10,478	$ (2,842)	$ 50,537	$ (33,740)
Net income (loss)	(21,799)	(21,200)	(105,680)	16,007
Accumulated Other Comprehensive Loss
Accumulated other comprehensive income (loss) components which were reclassified to the Consolidated Statement of Operations
Net income (loss)			0
Total reclassifications for the period	365		1,097
Defined benefit pension plan
Accumulated other comprehensive income (loss) components which were reclassified to the Consolidated Statement of Operations
Reclassifications for the period, before tax	574		1,724
Reclassifications for the period, tax	(209)		(627)
Total reclassifications for the period	$ 365		$ 1,097
Defined benefit pension plan | Reclassification out of AOCI
Accumulated other comprehensive income (loss) components which were reclassified to the Consolidated Statement of Operations
Reclassifications for the period, before tax		493		1,479
Reclassifications for the period, tax		(179)		(539)
Total reclassifications for the period		$ 314		$ 940