Retirement Benefit Plans - Net Pension Expense for Defined Benefit Plans (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
Components of net periodic benefit cost
Service cost	$ 280	$ 148
Interest cost	1,017	978
United States Pension Plan of US Entity
Components of net periodic benefit cost
Service cost	280	148
Interest cost	1,017	978
Expected return on plan assets	(1,632)	(1,671)
Amortization of net loss	828	545
Settlement cost	223	0
Net pension expense for defined benefit plan	$ 716	$ 0