Segment Information - Reconciliation of Reportable Segment Operating Income (Loss) to Corresponding Consolidated Amounts (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2020	Mar. 31, 2019
Segment Reporting Information [Line Items]
Total revenue	$ 220,227	$ 198,390	$ 430,727	$ 377,757
Amortization of intangible assets			20,900	17,200
Acquisition accounting impact on inventory contracts acquired				184
Operating income	14,572	13,672	25,238	19,004
Restructuring charges	578	370	1,154	429
Interest income	137	316	836	739
Interest expense	(718)	(8,018)	(1,455)	(13,308)
Loss on extinguishment of debt		(9,051)		(9,051)
Other expenses, net	(1,399)	(778)	(1,816)	(807)
Income before income taxes	12,592	(3,859)	22,803	(3,423)
Brooks Semiconductor Solutions Group
Segment Reporting Information [Line Items]
Total revenue	124,923	112,877	243,734	225,584
Operating income	16,707	18,903	31,707	36,166
Brooks Life Sciences
Segment Reporting Information [Line Items]
Total revenue	95,304	85,513	186,993	152,173
Operating income	8,117	5,018	14,091	7,678
Reportable Segments
Segment Reporting Information [Line Items]
Total revenue	220,227	198,390	430,727	377,757
Segment Reconciling Items
Segment Reporting Information [Line Items]
Operating income	24,824	23,921	45,798	43,844
Corporate, Non-Segment
Segment Reporting Information [Line Items]
Other unallocated corporate (income) expenses	(681)	474	(1,535)	7,047
Completed Technology
Segment Reporting Information [Line Items]
Amortization of intangible assets	2,740	2,791	5,416	4,798
Acquired Intangible Assets
Segment Reporting Information [Line Items]
Amortization of intangible assets	$ 7,615	$ 6,614	$ 15,525	$ 12,382