Segment Information - Financial Information for Business Segments - Statement of Operations (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Mar. 31, 2019	Dec. 31, 2018	Mar. 31, 2018	Mar. 31, 2019	Mar. 31, 2018
Revenue
Revenue	$ 198,390	$ 179,368	$ 156,952	$ 377,757	$ 299,551
Gross profit	80,516		62,386	152,596	116,645
Segment operating income (loss)	13,672		10,321	19,004	15,246
Products
Revenue
Revenue	128,056	125,375	121,031	253,430	226,803
Services
Revenue
Revenue	70,334	53,993	35,921	124,327	72,748
Brooks Semiconductor Solutions Group
Revenue
Revenue	112,877		108,413	225,584	203,570
Gross profit	45,987		43,457	91,901	81,952
Brooks Semiconductor Solutions Group \| Products
Revenue
Revenue	102,195		97,565	203,996	181,356
Brooks Semiconductor Solutions Group \| Services
Revenue
Revenue	10,682		10,848	21,588	22,214
Brooks Life Sciences
Revenue
Revenue	85,513	66,661	48,539	152,173	95,981
Gross profit	34,529		18,929	60,695	34,693
Brooks Life Sciences \| Products
Revenue
Revenue	25,861	23,574	23,466	49,434	45,447
Brooks Life Sciences \| Services
Revenue
Revenue	59,652	$ 43,087	25,073	102,739	50,534
Operating Segments
Revenue
Segment operating income (loss)	21,130		16,920	38,861	27,244
Depreciation expense	4,779		3,035	8,466	5,610
Operating Segments \| Brooks Semiconductor Solutions Group
Revenue
Segment operating income (loss)	17,987		15,424	34,128	27,143
Depreciation expense	1,017		996	1,934	2,022
Operating Segments \| Brooks Life Sciences
Revenue
Segment operating income (loss)	3,143		1,496	4,733	101
Depreciation expense	$ 3,762		$ 2,039	$ 6,532	$ 3,588

The amount of expense recognized in the current period that reflects the allocation of the cost of tangible assets over the assets' useful lives. Includes production and non-production related depreciation.

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