Leases - Assets and Liabilities - Operating Leases (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Oct. 01, 2019
Assets and Liabilities, Lessee [Abstract]
Operating lease right-of-use assets	$ 36,224	$ 28,100
Accrued expenses and other current liabilities	$ 6,457
Operating Lease Liability Current, Statement of Financial Position	brks:AccruedExpensesAndOtherCurrentLiabilities
Long-term operating lease liabilities	$ 29,280
Total lease liability balance	$ 35,737	$ 27,100