Changes in Accumulated Other Comprehensive Income (Loss) by Component (Details) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Accumulated other comprehensive income (loss)
Balance	$ 341,989
Net current-period other comprehensive income (loss)	288	$ (1,205)
Balance	339,940
AOCI Attributable to Parent
Accumulated other comprehensive income (loss)
Balance	(87,953)	(61,828)
Other comprehensive income (loss) before classifications	(1,688)	(2,459)
Net current-period other comprehensive income (loss)	288	(1,205)
Balance	(87,665)	(63,033)
Defined Benefit Plans
Accumulated other comprehensive income (loss)
Amounts reclassified from accumulated other comprehensive income (loss), Tax expense or (benefit)	(1,150)	(738)
Defined Benefit Plans | Defined Benefit Pension Plans
Accumulated other comprehensive income (loss)
Balance	(62,985)	(42,800)
Amounts reclassified from accumulated other comprehensive income (loss), Tax expense or (benefit)	(890)	(513)
Net current-period other comprehensive income (loss)	1,530	872
Balance	(61,455)	(41,928)
Defined Benefit Plans | Postretirement Health Care Benefits
Accumulated other comprehensive income (loss)
Balance	(21,773)	(20,000)
Amounts reclassified from accumulated other comprehensive income (loss), Tax expense or (benefit)	(260)	(225)
Net current-period other comprehensive income (loss)	446	382
Balance	(21,327)	(19,618)
Amortization of Pension and Postretirement Plan items
Accumulated other comprehensive income (loss)
Amounts reclassified from accumulated other comprehensive income (loss), before tax	202	202
Amortization of Pension and Postretirement Plan items | Defined Benefit Pension Plans
Accumulated other comprehensive income (loss)
Amounts reclassified from accumulated other comprehensive income (loss), before tax	202	202
Actuarial losses
Accumulated other comprehensive income (loss)
Amounts reclassified from accumulated other comprehensive income (loss), before tax	2,924	1,790
Actuarial losses | Defined Benefit Pension Plans
Accumulated other comprehensive income (loss)
Amounts reclassified from accumulated other comprehensive income (loss), before tax	2,218	1,183
Actuarial losses | Postretirement Health Care Benefits
Accumulated other comprehensive income (loss)
Amounts reclassified from accumulated other comprehensive income (loss), before tax	706	607
Foreign Exchange
Accumulated other comprehensive income (loss)
Balance	(3,195)	972
Other comprehensive income (loss) before classifications	(1,688)	(2,459)
Net current-period other comprehensive income (loss)	(1,688)	(2,459)
Balance	$ (4,883)	$ (1,487)