Segment Information - Reconciliation of Reportable Segment Operating Income (Loss) to Corresponding Consolidated Amounts (Details) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Segment Reporting Information [Line Items]
Total revenue	$ 249,503	$ 210,500
Amortization of other intangible assets	9,700	10,600
Restructuring charges	87	576
Operating income	30,928	10,666
Interest income	76	699
Interest expense	(556)	(737)
Other income (expenses), net	1,329	(417)
Income (loss) before income taxes	31,777	10,211
Completed Technology
Segment Reporting Information [Line Items]
Amortization of other intangible assets	2,389	2,674
Acquired Intangible Assets
Segment Reporting Information [Line Items]
Amortization of other intangible assets	7,356	7,910
Brooks Semiconductor Solutions Group
Segment Reporting Information [Line Items]
Total revenue	131,358	118,811
Operating income	21,538	15,000
Brooks Life Sciences Products
Segment Reporting Information [Line Items]
Total revenue	45,511	29,724
Operating income	7,942	362
Brooks Life Sciences Services
Segment Reporting Information [Line Items]
Total revenue	72,634	61,965
Operating income	14,311	5,612
Reportable Segments
Segment Reporting Information [Line Items]
Total revenue	249,503	210,500
Segment Reconciling Items
Segment Reporting Information [Line Items]
Operating income	43,791	20,974
Corporate, Non-Segment
Segment Reporting Information [Line Items]
Other unallocated corporate expense (income)	$ 3,031	$ (852)