Revenue from Contracts with Customers - Disaggregated By Timing (Details) - USD ($) $ in Thousands	3 Months Ended			9 Months Ended
	Jun. 30, 2019	Dec. 31, 2018	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Disaggregation of Revenue [Line Items]
Total revenue	$ 203,880	$ 179,368	$ 172,363	$ 581,637	$ 471,914
Brooks Semiconductor Solutions Group
Disaggregation of Revenue [Line Items]
Total revenue	116,040		122,660	341,624	326,229
Brooks Life Sciences
Disaggregation of Revenue [Line Items]
Total revenue	87,840	$ 66,661	$ 49,703	240,013	$ 145,685
Point in time
Disaggregation of Revenue [Line Items]
Total revenue	139,031			410,807
Point in time | Brooks Semiconductor Solutions Group
Disaggregation of Revenue [Line Items]
Total revenue	115,910			339,537
Point in time | Brooks Life Sciences
Disaggregation of Revenue [Line Items]
Total revenue	23,121			71,270
Over time
Disaggregation of Revenue [Line Items]
Total revenue	64,849			170,830
Over time | Brooks Semiconductor Solutions Group
Disaggregation of Revenue [Line Items]
Total revenue	130			2,087
Over time | Brooks Life Sciences
Disaggregation of Revenue [Line Items]
Total revenue	$ 64,719			$ 168,743