CONSOLIDATING GUARANTOR AND NON-GUARANTOR FINANCIAL INFORMATION (Details) - Summary of consolidated cash flows - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
CASH FLOWS FROM OPERATING ACTIVITIES - CONTINUING OPERATIONS:
Net income	$ 53,429	$ 37,287	$ 125,678
Net (income) loss from discontinued operations	0	8,335	(92,423)
Net cash provided by operating activities	137,029	113,958	58,192
CASH FLOWS FROM INVESTING ACTIVITIES - CONTINUING OPERATIONS:
Acquisition of property, plant and equipment	(48,998)	(45,361)	(50,138)
Acquired business, net of cash acquired	(10,531)	(9,219)	(430,932)
Proceeds (payments) from sale of business	0	(9,500)	474,727
Insurance proceeds (payments)	0	(10,604)	8,254
Proceeds from sale of property, plant and equipment	352	280	663
Investment purchases	(130)	(149)	0
Net cash provided by (used in) investing activities - continuing operations	(59,307)	(74,553)	2,574
CASH FLOWS FROM FINANCING ACTIVITIES - CONTINUING OPERATIONS:
Proceeds from issuance of common stock	178,165	0	0
Purchase of shares for treasury	(7,479)	(1,478)	(45,605)
Proceeds from long-term debt	1,240,080	201,748	443,058
Payments of long-term debt	(1,308,915)	(218,248)	(300,993)
Change in short-term borrowings	0	(366)	144
Financing costs	(17,384)	(1,090)	(7,793)
Contingent consideration for acquired businesses	(1,733)	(1,686)	0
Acquisition costs	(1,733)
Purchase of ESOP shares			0
Dividends paid	(14,529)	(13,676)	(49,797)
Other, net	(15)	(180)	51
Net cash provided by (used) in financing activities - continuing operations	68,190	(34,976)	39,065
CASH FLOWS FROM DISCONTINUED OPERATIONS:
Net cash provided by (used in) discontinued operations	(2,577)	(2,123)	(78,927)
Effect of exchange rate changes on cash and equivalents	2,377	313	1,173
NET DECREASE IN CASH AND EQUIVALENTS	145,712	2,619	22,077
CASH AND EQUIVALENTS AT BEGINNING OF PERIOD	72,377	69,758	47,681
CASH AND EQUIVALENTS AT END OF PERIOD	218,089	72,377	69,758
Parent Company
CASH FLOWS FROM OPERATING ACTIVITIES - CONTINUING OPERATIONS:
Net income	53,429	37,287	125,678
Net (income) loss from discontinued operations		0	0
Net cash provided by operating activities	23,114	42,159	381,417
CASH FLOWS FROM INVESTING ACTIVITIES - CONTINUING OPERATIONS:
Acquisition of property, plant and equipment	(348)	(542)	(544)
Acquired business, net of cash acquired	0	(9,219)	(368,936)
Proceeds (payments) from sale of business		(9,500)	0
Insurance proceeds (payments)		(10,604)	8,254
Proceeds from sale of property, plant and equipment	0	0	0
Investment purchases	(130)	(149)
Net cash provided by (used in) investing activities - continuing operations	(478)	(30,014)	(361,226)
CASH FLOWS FROM FINANCING ACTIVITIES - CONTINUING OPERATIONS:
Proceeds from issuance of common stock	178,165
Purchase of shares for treasury	(7,479)	(1,478)	(45,605)
Proceeds from long-term debt	1,234,723	163,297	411,623
Payments of long-term debt	(1,272,688)	(173,345)	(269,478)
Change in short-term borrowings		0	0
Financing costs	(17,384)	(1,090)	(7,793)
Contingent consideration for acquired businesses		0
Acquisition costs	0
Purchase of ESOP shares			0
Dividends paid	(14,529)	(13,676)	(49,797)
Other, net	260	(180)	(46,405)
Net cash provided by (used) in financing activities - continuing operations	101,068	(26,472)	(7,455)
CASH FLOWS FROM DISCONTINUED OPERATIONS:
Net cash provided by (used in) discontinued operations	0	0	0
Effect of exchange rate changes on cash and equivalents	0	0	0
NET DECREASE IN CASH AND EQUIVALENTS	123,704	(14,327)	12,736
CASH AND EQUIVALENTS AT BEGINNING OF PERIOD	1,649	15,976	3,240
CASH AND EQUIVALENTS AT END OF PERIOD	125,353	1,649	15,976
Guarantor Companies
CASH FLOWS FROM OPERATING ACTIVITIES - CONTINUING OPERATIONS:
Net income	101,960	94,637	122,687
Net (income) loss from discontinued operations		0	(92,423)
Net cash provided by operating activities	55,353	41,992	(405,174)
CASH FLOWS FROM INVESTING ACTIVITIES - CONTINUING OPERATIONS:
Acquisition of property, plant and equipment	(42,268)	(38,872)	(41,531)
Acquired business, net of cash acquired	0	0	(4,843)
Proceeds (payments) from sale of business		0	474,727
Insurance proceeds (payments)		0	0
Proceeds from sale of property, plant and equipment	345	254	62
Investment purchases	0	0
Net cash provided by (used in) investing activities - continuing operations	(41,923)	(38,618)	428,415
CASH FLOWS FROM FINANCING ACTIVITIES - CONTINUING OPERATIONS:
Proceeds from issuance of common stock	0
Purchase of shares for treasury	0	0	0
Proceeds from long-term debt	0	0	2,125
Payments of long-term debt	(3,421)	(2,973)	(5,403)
Change in short-term borrowings		(366)	144
Financing costs	0	0	0
Contingent consideration for acquired businesses		0
Acquisition costs	0
Purchase of ESOP shares			0
Dividends paid	0	0	0
Other, net	580	8,830	4,733
Net cash provided by (used) in financing activities - continuing operations	(2,841)	5,491	1,599
CASH FLOWS FROM DISCONTINUED OPERATIONS:
Net cash provided by (used in) discontinued operations	0	0	(16,394)
Effect of exchange rate changes on cash and equivalents	(121)	(1)	(159)
NET DECREASE IN CASH AND EQUIVALENTS	10,468	8,864	8,287
CASH AND EQUIVALENTS AT BEGINNING OF PERIOD	25,217	16,353	8,066
CASH AND EQUIVALENTS AT END OF PERIOD	35,685	25,217	16,353
Non-Guarantor Companies
CASH FLOWS FROM OPERATING ACTIVITIES - CONTINUING OPERATIONS:
Net income	102,002	81,089	84,680
Net (income) loss from discontinued operations		8,335	0
Net cash provided by operating activities	58,562	29,807	108,981
CASH FLOWS FROM INVESTING ACTIVITIES - CONTINUING OPERATIONS:
Acquisition of property, plant and equipment	(6,382)	(5,947)	(8,063)
Acquired business, net of cash acquired	(10,531)	0	(57,153)
Proceeds (payments) from sale of business		0	0
Insurance proceeds (payments)		0	0
Proceeds from sale of property, plant and equipment	7	26	601
Investment purchases	0	0
Net cash provided by (used in) investing activities - continuing operations	(16,906)	(5,921)	(64,615)
CASH FLOWS FROM FINANCING ACTIVITIES - CONTINUING OPERATIONS:
Proceeds from issuance of common stock	0
Purchase of shares for treasury	0	0	0
Proceeds from long-term debt	5,357	38,451	29,310
Payments of long-term debt	(32,806)	(41,930)	(26,112)
Change in short-term borrowings		0	0
Financing costs	0	0	0
Contingent consideration for acquired businesses		(1,686)
Acquisition costs	(1,733)
Purchase of ESOP shares			0
Dividends paid	0	0	0
Other, net	(855)	(8,830)	14,691
Net cash provided by (used) in financing activities - continuing operations	(30,037)	(13,995)	17,889
CASH FLOWS FROM DISCONTINUED OPERATIONS:
Net cash provided by (used in) discontinued operations	(2,577)	(2,123)	(62,533)
Effect of exchange rate changes on cash and equivalents	2,498	314	1,332
NET DECREASE IN CASH AND EQUIVALENTS	11,540	8,082	1,054
CASH AND EQUIVALENTS AT BEGINNING OF PERIOD	45,511	37,429	36,375
CASH AND EQUIVALENTS AT END OF PERIOD	57,051	45,511	37,429
Elimination
CASH FLOWS FROM OPERATING ACTIVITIES - CONTINUING OPERATIONS:
Net income	(203,962)	(175,726)	(207,367)
Net (income) loss from discontinued operations		0	0
Net cash provided by operating activities	0	0	(27,032)
CASH FLOWS FROM INVESTING ACTIVITIES - CONTINUING OPERATIONS:
Acquisition of property, plant and equipment	0	0	0
Acquired business, net of cash acquired	0	0	0
Proceeds (payments) from sale of business		0	0
Insurance proceeds (payments)		0	0
Proceeds from sale of property, plant and equipment	0	0	0
Investment purchases	0	0
Net cash provided by (used in) investing activities - continuing operations	0	0	0
CASH FLOWS FROM FINANCING ACTIVITIES - CONTINUING OPERATIONS:
Proceeds from issuance of common stock	0
Purchase of shares for treasury	0	0	0
Proceeds from long-term debt	0	0	0
Payments of long-term debt	0	0	0
Change in short-term borrowings		0	0
Financing costs	0	0	0
Contingent consideration for acquired businesses		0
Acquisition costs	0
Purchase of ESOP shares			0
Dividends paid	0	0	0
Other, net	0	0	27,032
Net cash provided by (used) in financing activities - continuing operations	0	0	27,032
CASH FLOWS FROM DISCONTINUED OPERATIONS:
Net cash provided by (used in) discontinued operations	0	0	0
Effect of exchange rate changes on cash and equivalents	0	0	0
NET DECREASE IN CASH AND EQUIVALENTS	0	0	0
CASH AND EQUIVALENTS AT BEGINNING OF PERIOD	0	0	0
CASH AND EQUIVALENTS AT END OF PERIOD	$ 0	$ 0	$ 0