Comprehensive Income (Loss) and Changes in Accumulated Other Comprehensive Income (Loss) by Component (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2011
Comprehensive Income (Loss) and Changes in Accumulated Other Comprehensive Income (Loss) by Component
Net income	$ 5,835	$ 4,009	$ 5,297	$ 6,436	$ 12,856	$ 13,732	$ 15,151	$ 8,443	$ 21,577	$ 50,182	$ 31,128
Pension and postretirement:
Net gain (loss) arising during period									74,282	(19,688)	(24,316)
Less: amortization of prior service cost									4,981	4,981	4,981
Less: amortization of gain (loss)									(13,906)	(11,830)	(8,991)
Foreign currency translation adjustment									1,012	698	645
Other comprehensive income (loss)									66,369	(25,839)	(27,681)
Pension and postretirement:
Net gain (loss) arising during period									(27,201)	7,399	10,670
Less: amortization of prior service cost									(1,743)	(1,743)	(1,743)
Less: amortization of gain (loss)									4,867	4,140	1,743
Other comprehensive income (loss)									(24,077)	9,796	10,670
Pension and postretirement:
Net gain (loss) arising during period									47,081	(12,289)	(13,646)
Less: amortization of prior service cost									3,238	3,238	3,238
Less: amortization of gain (loss)									(9,039)	(7,690)	(7,248)
Foreign currency translation adjustment									1,012	698	645
Other comprehensive income (loss)									42,292	(16,043)	(17,011)
Comprehensive income									$ 63,869	$ 34,139	$ 14,117