Segment Information - Financial Information for Business Segments - Statement of Operations (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
Revenue
Revenue	$ 203,880	$ 179,368	$ 172,363	$ 581,637	$ 471,914
Gross profit	83,510		66,815	236,106	183,461
Segment operating income	16,423		12,547	35,427	27,794
Products
Revenue
Revenue	128,397	125,375	135,278	381,827	362,082
Services
Revenue
Revenue	75,483	53,993	37,085	199,810	109,832
Brooks Semiconductor Solutions Group
Revenue
Revenue	116,040		122,660	341,624	326,229
Gross profit	47,493		48,227	139,393	130,180
Brooks Semiconductor Solutions Group \| Products
Revenue
Revenue	105,443		111,840	309,439	293,196
Brooks Semiconductor Solutions Group \| Services
Revenue
Revenue	10,597		10,820	32,185	33,033
Brooks Life Sciences
Revenue
Revenue	87,840	66,661	49,703	240,013	145,685
Gross profit	36,017		18,588	96,713	53,281
Brooks Life Sciences \| Products
Revenue
Revenue	22,954	23,574	23,438	72,388	68,886
Brooks Life Sciences \| Services
Revenue
Revenue	64,886	$ 43,087	26,265	167,625	76,799
Operating Segments
Revenue
Segment operating income	23,524		18,592	62,386	45,836
Depreciation expense	4,700		2,902	13,166	8,457
Operating Segments \| Brooks Semiconductor Solutions Group
Revenue
Segment operating income	19,322		17,915	53,450	45,058
Depreciation expense	504		911	2,438	2,878
Operating Segments \| Brooks Life Sciences
Revenue
Segment operating income	4,202		677	8,936	778
Depreciation expense	$ 4,196		$ 1,991	$ 10,728	$ 5,579

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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