Pension Plans (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2017	Mar. 31, 2016
Components of net periodic pension cost (benefit)
Service cost	$ 151	$ 152	$ 302	$ 310
Interest cost	1,759	2,279	3,518	4,540
Expected return on plan assets	(3,201)	(3,303)	(6,400)	(6,775)
Amortization of actuarial loss	912	499	1,822	912
Administrative expenses	47	45	94	86
Net pension benefit	$ (332)	$ (328)	$ (664)	$ (927)