Significant Accounting Policies - Income Taxes (Details) $ in Millions	12 Months Ended
Oct. 03, 2020 USD ($)
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Tax expense against our foreign earnings not indefinitely reinvested	$ 16.1

Tax expense against our foreign earnings not indefinitely reinvested

No definition available.

Name:	cohr_TaxExpenseAgainstOurForeignEarningsNotIndefinitelyReinvested
Namespace Prefix:	cohr_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration