Leases - Assets and Liabilities - Operating Leases (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Oct. 01, 2019
Assets and Liabilities, Lessee [Abstract]
Operating lease right-of-use assets	$ 34,671	$ 28,100
Accrued expenses and other current liabilities	$ 6,841
Operating Lease Liability Current, Statement of Financial Position	brks:AccruedExpensesAndOtherCurrentLiabilities
Long-term operating lease liabilities	$ 27,233
Total lease liability balance	$ 34,074	$ 27,100