Consolidated Statements Of Comprehensive Income (Loss) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2014
Statement of Comprehensive Income [Abstract]
Net income	$ (54,465)	$ 47,557	$ 160,194
Other comprehensive income (loss), net of tax:
Unrealized hedge gain (loss) arising during the period	(3,375)	0	0
Net hedge loss reclassified into earnings	2,131	0	0
Unrealized loss on hedging instruments	(1,244)	0	0
Foreign currency translation adjustment, net of tax of $0 for all periods	408	(47,177)	(24,069)
Unrealized loss on marketable securities, net of tax	(122)	0	0
Amortization of net actuarial pension loss included in net income, net of tax of $0.7 million, $18.5 million, and $0.3 million in 2016, 2015 and 2014, respectively	1,609	52,249	3,048
Pension net loss arising during the period net of tax of $3.5 million, $1.6 million and $2.8 million in 2016, 2015, and 2014, respectively	(8,646)	(4,797)	(24,267)
Change in unamortized pension loss during the period related to changes in foreign currency	(216)	2,350	2,081
Other comprehensive income (loss)	(8,211)	2,625	(43,207)
Comprehensive income (loss)	$ (62,676)	$ 50,182	$ 116,987