Segment Information - Financial Information for Business Segments (Detail) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Sep. 30, 2016
Revenue
Products	$ 122,114	$ 89,180
Services	37,841	30,775
Total revenue	159,955	119,955
Gross profit	56,943	40,554
Segment operating income (loss)	13,161	(8,320)
Total assets	692,307		$ 685,905
Brooks Semiconductor Solutions Group
Revenue
Products	109,395	79,179
Services	17,221	19,897
Total revenue	126,616	99,076
Gross profit	45,468	34,659
Segment operating income (loss)	17,371	2,940
Depreciation expense	1,275	886
Total assets	310,894		317,717
Brooks Life Science Systems
Revenue
Products	12,719	10,001
Services	20,620	10,878
Total revenue	33,339	20,879
Gross profit	11,475	5,895
Segment operating income (loss)	112	(4,602)
Depreciation expense	1,090	488
Total assets	265,431		247,735
Operating Segments
Revenue
Products	122,114	89,180
Services	37,841	30,775
Total revenue	159,955	119,955
Gross profit	56,943	40,554
Segment operating income (loss)	17,483	(1,662)
Depreciation expense	2,365	$ 1,374
Total assets	$ 576,325		$ 565,452