Borrowings - Borrowings obligation table (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Jun. 30, 2018	Sep. 30, 2017
Short-term Debt [Line Items]
Total short-term borrowings and current portion of long-term obligations	$ 7,076	$ 5,078
Euro term loan
Short-term Debt [Line Items]
Debt issuance cost for long term portion of the Euro term loan	13,800	20,400
Euro term loan
Short-term Debt [Line Items]
Debt issuance cost for short term Euro term loan	3,400	4,700
Short-term Debt
Short-term Debt [Line Items]
Euro Term Loan due 2024	4,445	3,230
1.3% Term loan due 2024	1,454	1,477
1.0% State of Connecticut term loan due 2023	373	371
O.R. Lasertech loans	158	0
Line of credit borrowings	646	0
Total short-term borrowings and current portion of long-term obligations	7,076	5,078
Long-term Debt
Short-term Debt [Line Items]
Euro Term Loan due 2024	412,716	578,356
1.3% Term loan due 2024	7,635	8,865
1.0% State of Connecticut term loan due 2023	1,500	1,780
O.R. Lasertech loans	434	0
Total long-term obligations	$ 422,285	$ 589,001