Segment and Geographic Information - Financial Information for Business Segments (Detail) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2014
Revenue
Products	$ 421,783	$ 457,411	$ 387,032
Services	138,540	95,297	95,816
Total revenue	560,323	552,708	482,848
Gross profit	198,081	189,105	167,337
Segment operating income (loss)	4,238	16,890	(2,699)
Depreciation expense	13,100	12,300	12,700
Total assets	685,905	758,702
Brooks Semiconductor Solutions Group
Revenue
Products	375,237	406,579	340,617
Services	76,973	78,058	79,083
Total revenue	452,210	484,637	419,700
Gross profit	159,018	171,379	143,914
Segment operating income (loss)	37,926	49,695	23,287
Depreciation expense	4,788	4,312	10,677
Total assets	317,717	317,069	311,622
Brooks Life Science Systems
Revenue
Products	46,546	50,832	46,415
Services	61,567	17,239	16,733
Total revenue	108,113	68,071	63,148
Gross profit	39,063	17,726	23,423
Segment operating income (loss)	(6,451)	(19,580)	(8,431)
Depreciation expense	3,496	1,295	2,022
Total assets	247,735	110,910	103,498
Operating Segments, Total
Revenue
Products	421,783	457,411	387,032
Services	138,540	95,297	95,816
Total revenue	560,323	552,708	482,848
Gross profit	198,081	189,105	167,337
Segment operating income (loss)	31,476	30,115	14,856
Depreciation expense	8,284	5,607	12,699
Total assets	$ 565,452	$ 427,979	$ 415,120