Business Segments (Details) $ in Thousands		3 Months Ended								12 Months Ended
	Oct. 29, 2018 segment	Sep. 30, 2020 USD ($) segment	Jun. 30, 2020 USD ($)	Mar. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Sep. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)	Mar. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Sep. 30, 2020 USD ($) segment	Sep. 30, 2019 USD ($)	Sep. 30, 2018 USD ($)	Oct. 01, 2019 USD ($)
Segment Reporting [Abstract]
Number of reportable segments | segment	3	2								2
Segment Reporting Information [Line Items]
Revenue										$ 1,429,456	$ 1,444,441	$ 1,339,541
Sales to external customers		$ 383,861	$ 347,827	$ 351,663	$ 346,105	$ 412,468	$ 360,343	$ 348,628	$ 323,002	1,429,456	1,444,441	1,339,541
Earnings before interest, taxes, depreciation and amortization (EBITDA)										168,448	59,672	66,846
Depreciation and amortization										107,268	98,236	85,860
Interest expense		(9,362)	(10,485)	(13,252)	(13,583)	(14,797)	(14,842)	(14,474)	(14,443)	(46,682)	(58,556)	(57,580)
Income before income taxes										121,766	1,116	9,266
Income tax expense		(4,035)	(740)	7	(2,603)	(10,721)	(7,959)	4,579	4,514	(7,371)	(9,587)	(1,382)
Net income (loss)		31,138	$ 21,841	$ 7,910	$ 53,506	1,954	$ 4,290	$ 1,573	$ (16,288)	114,395	(8,471)	7,884
Capital expenditures										88,456	88,869	80,713
Assets		1,844,458				1,737,848				1,844,458	1,737,848		$ 1,782,660
Goodwill		397,205				392,890				397,205	392,890	411,346
Integrated Solutions and Services
Segment Reporting Information [Line Items]
Sales to external customers										944,182	910,834
Capital expenditures										75,551	73,656	58,464
Goodwill												224,370
Applied Product Technologies
Segment Reporting Information [Line Items]
Sales to external customers										485,274	533,607
Capital expenditures										6,237	7,589	11,501
Goodwill												186,976
Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenue										1,514,177	1,551,317	1,424,142
Operating Segments [Member] | Integrated Solutions and Services
Segment Reporting Information [Line Items]
Revenue										954,542	919,985	844,851
Sales to external customers										944,182		835,634
Earnings before interest, taxes, depreciation and amortization (EBITDA)										145,655	148,593	138,043
Depreciation and amortization										67,489	57,217	48,781
Assets		835,307				762,707				835,307	762,707
Goodwill		224,381				222,013				224,381	222,013
Operating Segments [Member] | Applied Product Technologies
Segment Reporting Information [Line Items]
Revenue										559,635	631,332	579,291
Sales to external customers										485,274		503,907
Earnings before interest, taxes, depreciation and amortization (EBITDA)										134,258	69,377	71,948
Depreciation and amortization										14,226	17,675	16,734
Assets		598,701				657,879				598,701	657,879
Goodwill		172,824				170,877				172,824	170,877
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Sales to external customers										84,721	106,876	84,601
Intersegment Eliminations [Member] | Integrated Solutions and Services
Segment Reporting Information [Line Items]
Sales to external customers										10,360	9,151	9,217
Intersegment Eliminations [Member] | Applied Product Technologies
Segment Reporting Information [Line Items]
Sales to external customers										74,361	97,725	75,384
Corporate, Non-Segment [Member]
Segment Reporting Information [Line Items]
Earnings before interest, taxes, depreciation and amortization (EBITDA)										(111,465)	(158,298)	(143,145)
Depreciation and amortization										25,553	23,344	20,345
Capital expenditures										6,668	7,624	$ 10,748
Assets		$ 410,450				$ 317,262				$ 410,450	$ 317,262