Business Segments (Details) $ in Thousands			3 Months Ended		6 Months Ended
	Oct. 30, 2018	Oct. 29, 2018	Mar. 31, 2019 USD ($)	Mar. 31, 2018 USD ($)	Mar. 31, 2019 USD ($) segment	Mar. 31, 2018 USD ($)	Sep. 30, 2018 USD ($)
Segment Reporting [Abstract]
Number of reportable segments	2	3	2		2
Segment Reporting Information [Line Items]
Revenue from product sales and services			$ 348,628	$ 333,690	$ 671,630	$ 630,740
Revenues			348,628	333,690	671,630	630,740
Earnings before interest, taxes, depreciation and amortization (EBITDA)			35,630	46,288	52,361	75,998
Depreciation and amortization			24,162	20,480	47,252	40,363
Operating profit (loss)			11,468	25,808	5,109	35,635
Interest expense			(14,474)	(10,810)	(28,917)	(28,053)
(Loss) income before income taxes			(3,006)	14,998	(23,808)	7,582
Income tax (expense) benefit			4,579	(2,018)	9,093	2,393
Net (loss) income			1,573	12,980	(14,715)	9,975
Capital expenditures			23,113	16,413	40,682	31,670
Assets			1,660,174		1,660,174		$ 1,663,617
Goodwill			407,572		407,572		411,346
Integrated Solutions and Services
Segment Reporting Information [Line Items]
Revenue from product sales and services			226,864
Revenues					437,362
Capital expenditures			19,972	12,359	33,657	21,923
Applied Product Technologies
Segment Reporting Information [Line Items]
Revenue from product sales and services			121,764
Revenues					234,268
Capital expenditures			2,060	1,562	4,268	3,875
Intersegment Eliminations
Segment Reporting Information [Line Items]
Revenue from product sales and services			28,447	21,995	48,256	44,079
Intersegment Eliminations | Integrated Solutions and Services
Segment Reporting Information [Line Items]
Revenue from product sales and services			2,075	2,740	3,854	5,884
Intersegment Eliminations | Applied Product Technologies
Segment Reporting Information [Line Items]
Revenue from product sales and services			26,372	19,255	44,402	38,195
Operating Segments
Segment Reporting Information [Line Items]
Revenue from product sales and services			377,075	355,685	719,886	674,819
Operating Segments | Integrated Solutions and Services
Segment Reporting Information [Line Items]
Revenue from product sales and services			228,939	207,215	441,216	402,265
Revenues			226,864	204,475	437,362	396,381
Earnings before interest, taxes, depreciation and amortization (EBITDA)			51,325	46,126	93,209	91,312
Depreciation and amortization			14,314	11,479	28,272	22,622
Operating profit (loss)			37,011	34,647	64,937	68,690
Assets			721,000		721,000		711,622
Goodwill			220,970		220,970		224,370
Operating Segments | Applied Product Technologies
Segment Reporting Information [Line Items]
Revenue from product sales and services			148,136	148,470	278,670	272,554
Revenues			121,764	129,215	234,268	234,359
Earnings before interest, taxes, depreciation and amortization (EBITDA)			15,779	28,082	24,630	40,131
Depreciation and amortization			4,458	3,999	8,792	7,894
Operating profit (loss)			11,321	24,083	15,838	32,237
Assets			664,381		664,381		677,993
Goodwill			186,602		186,602		186,976
Corporate, Non-Segment
Segment Reporting Information [Line Items]
Earnings before interest, taxes, depreciation and amortization (EBITDA)			(31,474)	(27,920)	(65,478)	(55,445)
Depreciation and amortization			5,390	5,002	10,188	9,847
Operating profit (loss)			(36,864)	(32,922)	(75,666)	(65,292)
Capital expenditures			1,081	$ 2,492	2,757	$ 5,872
Assets			$ 274,793		$ 274,793		$ 274,002