Borrowings - Borrowings obligation table (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
Dec. 29, 2018	Sep. 29, 2018
Short-term Debt [Line Items]
Total short-term borrowings and current portion of long-term obligations	$ 46,670	$ 5,072
Euro term loan
Short-term Debt [Line Items]
Debt issuance cost for long term portion of the Euro term loan	9,900	11,200
Euro term loan
Short-term Debt [Line Items]
Debt issuance cost for short term Euro term loan	4,600	4,700
Short-term Debt
Short-term Debt [Line Items]
Euro Term Loan due 2024	3,065	3,092
1.3% Term loan due 2024	1,783	1,448
1.0% State of Connecticut term loan due 2023	375	374
OR Laser loans	158	158
Capital lease obligations	270	0
Line of credit borrowings	41,019	0
Total short-term borrowings and current portion of long-term obligations	46,670	5,072
Long-term Debt
Short-term Debt [Line Items]
Euro Term Loan due 2024	404,562	411,661
1.3% Term loan due 2024	6,775	7,242
1.0% State of Connecticut term loan due 2023	1,312	1,406
OR Laser loans	364	402
Capital lease obligations	492	0
Long-term Debt	$ 413,505	$ 420,711

1.0% State of Connecticut Term Loan due 2023

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1.3% Term Loan due 2024

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Capital lease obligation

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Debt issuance cost for long term portion of the Euro term loan

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Debt issuance cost for short term portion of the Euro term loan

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O.R. Lasertech loans

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Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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