CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE INCOME - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
Income Statement [Abstract]
Revenue	$ 2,407,522	$ 2,209,289	$ 1,977,918
Cost of goods and services	1,766,096	1,625,815	1,466,600
Gross profit	641,426	583,474	511,318
Selling, general and administrative expenses	486,398	447,163	418,517
Income from continuing operations	155,028	136,311	92,801
Other income (expense)
Interest expense	(66,544)	(68,066)	(65,568)
Interest income	753	806	1,697
Loss from debt extinguishment	(7,925)	0	0
Other, net	1,445	3,127	4,880
Total other income (expense)	(72,271)	(64,133)	(58,991)
Income before taxes from continuing operations	82,757	72,178	33,810
Provision for income taxes	29,328	26,556	555
Income (loss) from continuing operations	53,429	45,622	33,255
Discontinued operations:
Income (loss) from operations of discontinued businesses	0	(11,050)	119,981
Provision for income taxes	0	(2,715)	27,558
Income (loss) from discontinued operations	0	(8,335)	92,423
Net income	$ 53,429	$ 37,287	$ 125,678
Income from continuing operations (in usd per share)	$ 1.25	$ 1.11	$ 0.81
Income from discontinued operations (in usd per share)	0	(0.20)	2.25
Basic earnings per common share (in usd per share)	$ 1.25	$ 0.91	$ 3.06
Weighted-average shares outstanding (in shares)	42,588	40,934	41,005
Income from continuing operations (in usd per share)	$ 1.19	$ 1.06	$ 0.78
Income from discontinued operations (in usd per share)	0	(0.20)	2.18
Diluted earnings per common share (in usd per share)	$ 1.19	$ 0.87	$ 2.96
Weighted-average shares outstanding (in shares)	45,015	42,888	42,422
Other comprehensive income (loss), net of taxes:
Foreign currency translation adjustments	$ 5,601	$ (8,460)	$ 9,403
Pension and other post retirement plans	(11,784)	(23,055)	16,381
Gain (loss) on cash flow hedge	7	(289)	585
Total other comprehensive income (loss), net of taxes	(6,176)	(31,804)	26,369
Comprehensive income	$ 47,253	$ 5,483	$ 152,047