Changes in Accumulated Other Comprehensive Income (Loss) by Component (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2015	Mar. 31, 2014
Accumulated other comprehensive income (loss)
Accumulated other comprehensive income (loss) at the beginning of the period	$ (63,033)	$ (54,798)	$ (61,828)	$ (56,799)
Other comprehensive income (loss) before classifications	(2,786)	391	(5,245)	1,681
Amounts reclassified from accumulated other comprehensive income (loss)	1,253	712	2,507	1,423
Net current-period other comprehensive income (loss)	(1,533)	1,103	(2,738)	3,104
Accumulated other comprehensive income (loss) at the end of the period	(64,566)	(53,695)	(64,566)	(53,695)
Defined Benefit Plans | Defined Benefit Pension Plans
Accumulated other comprehensive income (loss)
Accumulated other comprehensive income (loss) at the beginning of the period	(41,928)	(41,945)	(42,800)	(42,798)
Amounts reclassified from accumulated other comprehensive income (loss)	870	853	1,742	1,706
Net current-period other comprehensive income (loss)	870	853	1,742	1,706
Accumulated other comprehensive income (loss) at the end of the period	(41,058)	(41,092)	(41,058)	(41,092)
Defined Benefit Plans | Postretirement Health Care Benefits
Accumulated other comprehensive income (loss)
Accumulated other comprehensive income (loss) at the beginning of the period	(19,618)	(16,106)	(20,000)	(15,964)
Amounts reclassified from accumulated other comprehensive income (loss)	383	(141)	765	(283)
Net current-period other comprehensive income (loss)	383	(141)	765	(283)
Accumulated other comprehensive income (loss) at the end of the period	(19,235)	(16,247)	(19,235)	(16,247)
Foreign Exchange
Accumulated other comprehensive income (loss)
Accumulated other comprehensive income (loss) at the beginning of the period	(1,487)	3,253	972	1,963
Other comprehensive income (loss) before classifications	(2,786)	391	(5,245)	1,681
Net current-period other comprehensive income (loss)	(2,786)	391	(5,245)	1,681
Accumulated other comprehensive income (loss) at the end of the period	$ (4,273)	$ 3,644	$ (4,273)	$ 3,644