Revenue from Contracts with Customers - Disaggregated By Timing (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2020	Mar. 31, 2019
Disaggregation of Revenue [Line Items]
Total revenue	$ 220,227	$ 198,390	$ 430,727	$ 377,757
Brooks Semiconductor Solutions Group
Disaggregation of Revenue [Line Items]
Total revenue	124,923	112,877	243,734	225,584
Brooks Life Sciences
Disaggregation of Revenue [Line Items]
Total revenue	95,304	85,513	186,993	152,173
Point in time
Disaggregation of Revenue [Line Items]
Total revenue	147,035	136,693	285,143	271,776
Point in time | Brooks Semiconductor Solutions Group
Disaggregation of Revenue [Line Items]
Total revenue	122,694	111,710	239,483	223,626
Point in time | Brooks Life Sciences
Disaggregation of Revenue [Line Items]
Total revenue	24,341	24,983	45,660	48,150
Over time
Disaggregation of Revenue [Line Items]
Total revenue	73,192	61,697	145,584	105,981
Over time | Brooks Semiconductor Solutions Group
Disaggregation of Revenue [Line Items]
Total revenue	2,229	1,167	4,251	1,958
Over time | Brooks Life Sciences
Disaggregation of Revenue [Line Items]
Total revenue	$ 70,963	$ 60,530	$ 141,333	$ 104,023