Business Segments (Details) $ in Thousands		3 Months Ended		6 Months Ended
	Oct. 29, 2018 segment	Mar. 31, 2021 USD ($) segment	Mar. 31, 2020 USD ($)	Mar. 31, 2021 USD ($) segment	Mar. 31, 2020 USD ($)	Sep. 30, 2020 USD ($)
Segment Reporting [Abstract]
Number of reportable segments | segment	3	2		2
Segment Reporting Information [Line Items]
Revenue from product sales and services		$ 346,564	$ 351,663	$ 668,757	$ 697,768
Operating profit (loss)		16,178	21,155	32,412	90,847
Interest expense		(8,395)	(13,252)	(17,068)	(26,835)
Income (loss) before income taxes		7,783	7,903	15,344	64,012
Income tax (expense) benefit		(2,701)	7	(3,785)	(2,596)
Net income		5,082	7,910	11,559	61,416
Depreciation and amortization				54,607	52,514
Capital expenditures				36,297	38,759
Assets		1,879,799		1,879,799		$ 1,844,458
Goodwill		404,393		404,393		397,205
Integrated Solutions and Services
Segment Reporting Information [Line Items]
Revenue from product sales and services		224,134	237,885	438,851	466,023
Applied Product Technologies
Segment Reporting Information [Line Items]
Revenue from product sales and services		122,430	113,778	229,906	231,745
Intersegment Eliminations
Segment Reporting Information [Line Items]
Revenue from product sales and services		27,746	18,585	45,887	42,809
Intersegment Eliminations | Integrated Solutions and Services
Segment Reporting Information [Line Items]
Revenue from product sales and services		4,069	2,939	6,105	6,601
Intersegment Eliminations | Applied Product Technologies
Segment Reporting Information [Line Items]
Revenue from product sales and services		23,677	15,646	39,782	36,208
Operating Segments
Segment Reporting Information [Line Items]
Total revenue		374,310	370,248	714,644	740,577
Operating Segments | Integrated Solutions and Services
Segment Reporting Information [Line Items]
Total revenue		228,203	240,824	444,956	472,624
Revenue from product sales and services		224,134	237,885	438,851
Operating profit (loss)		30,784	36,695	57,141	69,849
Assets		831,558		831,558		835,307
Goodwill		229,449		229,449		224,381
Operating Segments | Applied Product Technologies
Segment Reporting Information [Line Items]
Total revenue		146,107	129,424	269,688	267,953
Revenue from product sales and services		122,430	113,778	229,906
Operating profit (loss)		18,103	23,750	31,483	86,892
Assets		612,320		612,320		598,701
Goodwill		174,944		174,944		172,824
Corporate, Non-Segment
Segment Reporting Information [Line Items]
Operating profit (loss)		(32,709)	$ (39,290)	(56,212)	$ (65,894)
Assets		$ 435,921		$ 435,921		$ 410,450