Pension and Post-retirement Benefits (Details) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Defined Benefit Pension Plans
Pension Plan and Retirement Benefits
Service cost	$ 1,020	$ 975
Interest cost	2,848	2,641
Expected return	(3,376)	(3,563)
Amortizations	2,381	1,361
Net periodic benefit cost	2,873	1,414
U.S. pension plan
Pension Plan and Retirement Benefits
Employer contribution	1,500
Expected future employer contribution	4,500
U.K. pension plan
Pension Plan and Retirement Benefits
Employer contribution	226
Expected future employer contribution	456
Postretirement Health Care Benefits
Pension Plan and Retirement Benefits
Service cost	58	84
Interest cost	1,149	1,096
Amortizations	706	609
Net periodic benefit cost	1,913	$ 1,789
Employer contribution	1,807
Expected future employer contribution	$ 3,063