CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE INCOME - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019
Income Statement [Abstract]
Revenue	$ 2,270,626	$ 2,066,546	$ 1,874,248
Cost of goods and services	1,629,513	1,482,552	1,357,403
Gross profit	641,113	583,994	516,845
Selling, general and administrative expenses	470,530	444,454	408,339
Income from continuing operations	170,583	139,540	108,506
Other income (expense)
Interest expense	(63,175)	(66,544)	(68,312)
Interest income	440	749	799
Loss from debt extinguishment	0	(7,925)	0
Other, net	3,331	2,885	5,230
Total other income (expense)	(59,404)	(70,835)	(62,283)
Income (loss) before taxes from continuing operations	111,179	68,705	46,223
Provision for income taxes	39,940	26,262	20,753
Income (loss) from continuing operations	71,239	42,443	25,470
Discontinued operations:
Income before tax from discontinued operations	8,897	14,052	14,905
Provision for income taxes	925	3,066	3,088
Income from discontinued operations	7,972	10,986	11,817
Net income	$ 79,211	$ 53,429	$ 37,287
Basic earnings per common share:
Income from continuing operations (in usd per share)	$ 1.40	$ 1.00	$ 0.62
Income from discontinued operations (in usd per share)	0.16	0.26	0.29
Basic earnings per common share (in usd per share)	$ 1.56	$ 1.25	$ 0.91
Weighted-average shares outstanding (in shares)	50,830	42,588	40,934
Diluted earnings per common share:
Income from continuing operations (in usd per share)	$ 1.33	$ 0.94	$ 0.59
Income from discontinued operations (in usd per share)	0.15	0.24	0.28
Diluted earnings per common share (in usd per share)	$ 1.48	$ 1.19	$ 0.87
Weighted-average shares outstanding (in shares)	53,369	45,015	42,888
Other comprehensive income (loss), net of taxes:
Foreign currency translation adjustments	$ 6,433	$ 5,601	$ (8,460)
Pension and other post retirement plans	17,796	(11,784)	(23,055)
Gain (loss) on cash flow hedge	1,886	7	(289)
Total other comprehensive income (loss), net of taxes	26,115	(6,176)	(31,804)
Comprehensive income	$ 105,326	$ 47,253	$ 5,483