Pension and Post-retirement Benefits (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Defined Benefit Pension Plans
Pension Plan and Retirement Benefits
Service cost	$ 975	$ 993	$ 2,924	$ 2,978
Interest cost	2,787	2,953	8,010	8,653
Expected return	(3,761)	(3,702)	(10,807)	(10,846)
Amortizations	1,381	1,368	4,097	4,077
Net periodic benefit cost	1,382	1,612	4,224	4,862
U.S. pension plan
Pension Plan and Retirement Benefits
Expected future employer contribution			1,500
U.S. pension plan | Minimum
Pension Plan and Retirement Benefits
Employer contribution			800
U.K. pension plan
Pension Plan and Retirement Benefits
Employer contribution			694
Expected future employer contribution			281
Postretirement Health Care Benefits
Pension Plan and Retirement Benefits
Service cost	84	67	253	200
Interest cost	1,097	1,144	3,289	3,433
Amortizations	608	(224)	1,825	(673)
Net periodic benefit cost	$ 1,789	$ 987	5,367	$ 2,960
Employer contribution			3,346
Expected future employer contribution			$ 1,131