CONSOLIDATING GUARANTOR AND NON-GUARANTOR FINANCIAL INFORMATION - Condensed Consolidating Statements of Cash Flows (Details) - USD ($) $ in Thousands	3 Months Ended				6 Months Ended
	Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2019	Dec. 31, 2018	Mar. 31, 2020	Mar. 31, 2019
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 895	$ 10,612	$ (1,156)	$ 8,753	$ 11,507	$ 7,597
Net loss from discontinued operations	0		7,646		0	7,646
Net cash provided by (used in) operating activities:					(60,843)	(55,006)
CASH FLOWS FROM INVESTING ACTIVITIES:
Acquisition of property, plant and equipment	(9,347)		(9,021)		(22,519)	(17,418)
Acquired businesses, net of cash acquired					(10,531)	(9,219)
Investment purchase					0	(149)
Insurance payments					0	(10,604)
Proceeds from sale of assets					290	62
Net cash used in investing activities					(32,760)	(37,328)
CASH FLOWS FROM FINANCING ACTIVITIES:
Purchase of shares for treasury					(7,479)	(1,478)
Proceeds from long-term debt					1,061,343	143,101
Payments of long-term debt					(939,071)	(48,169)
Contingent consideration for acquired businesses					0	(1,686)
Financing costs					(13,176)	(945)
Dividends paid					(7,349)	(6,847)
Other, net					83	83
Net cash provided by financing activities					94,351	84,059
CASH FLOWS FROM DISCONTINUED OPERATIONS:
Net cash provided by (used) in discontinued operations					(1,994)	(3,438)
Effect of exchange rate changes on cash and equivalents					(2,107)	(66)
NET DECREASE IN CASH AND EQUIVALENTS					(3,353)	(11,779)
CASH AND EQUIVALENTS AT BEGINNING OF PERIOD		72,377		69,758	72,377	69,758
CASH AND EQUIVALENTS AT END OF PERIOD	69,024		57,979		69,024	57,979
Parent Company
CASH FLOWS FROM INVESTING ACTIVITIES:
Investment purchase						(149)
Guarantor Companies
CASH FLOWS FROM INVESTING ACTIVITIES:
Investment purchase						0
Non-Guarantor Companies
CASH FLOWS FROM INVESTING ACTIVITIES:
Investment purchase						0
Reportable Legal Entities | Parent Company
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	895		(1,156)		11,507	7,597
Net loss from discontinued operations			0			0
Net cash provided by (used in) operating activities:					(92,042)	(77,881)
CASH FLOWS FROM INVESTING ACTIVITIES:
Acquisition of property, plant and equipment					(282)	(210)
Acquired businesses, net of cash acquired					0	(9,219)
Insurance payments						(10,604)
Proceeds from sale of assets					0	0
Net cash used in investing activities					(282)	(20,182)
CASH FLOWS FROM FINANCING ACTIVITIES:
Purchase of shares for treasury					(7,479)	(1,478)
Proceeds from long-term debt					1,054,636	130,484
Payments of long-term debt					(921,904)	(32,419)
Contingent consideration for acquired businesses						0
Financing costs					(13,176)	(945)
Dividends paid					(7,349)	(6,847)
Other, net					(4,801)	(1,641)
Net cash provided by financing activities					99,927	87,154
CASH FLOWS FROM DISCONTINUED OPERATIONS:
Net cash provided by (used) in discontinued operations					0	0
Effect of exchange rate changes on cash and equivalents					0	0
NET DECREASE IN CASH AND EQUIVALENTS					7,603	(10,909)
CASH AND EQUIVALENTS AT BEGINNING OF PERIOD		1,649		15,976	1,649	15,976
CASH AND EQUIVALENTS AT END OF PERIOD	9,252		5,067		9,252	5,067
Reportable Legal Entities | Guarantor Companies
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	13,426		21,899		32,202	38,703
Net loss from discontinued operations			0			0
Net cash provided by (used in) operating activities:					26,593	24,130
CASH FLOWS FROM INVESTING ACTIVITIES:
Acquisition of property, plant and equipment					(19,982)	(14,071)
Acquired businesses, net of cash acquired					0	0
Insurance payments						0
Proceeds from sale of assets					292	36
Net cash used in investing activities					(19,690)	(14,035)
CASH FLOWS FROM FINANCING ACTIVITIES:
Purchase of shares for treasury					0	0
Proceeds from long-term debt					0	76
Payments of long-term debt					(1,752)	(1,724)
Contingent consideration for acquired businesses						0
Financing costs					0	0
Dividends paid					0	0
Other, net					(10,839)	7,150
Net cash provided by financing activities					(12,591)	5,502
CASH FLOWS FROM DISCONTINUED OPERATIONS:
Net cash provided by (used) in discontinued operations					0	0
Effect of exchange rate changes on cash and equivalents					(552)	(92)
NET DECREASE IN CASH AND EQUIVALENTS					(6,240)	15,505
CASH AND EQUIVALENTS AT BEGINNING OF PERIOD		25,217		16,353	25,217	16,353
CASH AND EQUIVALENTS AT END OF PERIOD	18,977		31,858		18,977	31,858
Reportable Legal Entities | Non-Guarantor Companies
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	13,378		7,652		32,034	24,499
Net loss from discontinued operations			7,646			7,646
Net cash provided by (used in) operating activities:					4,606	(1,255)
CASH FLOWS FROM INVESTING ACTIVITIES:
Acquisition of property, plant and equipment					(2,255)	(3,137)
Acquired businesses, net of cash acquired					(10,531)	0
Insurance payments						0
Proceeds from sale of assets					(2)	26
Net cash used in investing activities					(12,788)	(3,111)
CASH FLOWS FROM FINANCING ACTIVITIES:
Purchase of shares for treasury					0	0
Proceeds from long-term debt					6,707	12,541
Payments of long-term debt					(15,415)	(14,026)
Contingent consideration for acquired businesses						(1,686)
Financing costs					0	0
Dividends paid					0	0
Other, net					15,723	(5,426)
Net cash provided by financing activities					7,015	(8,597)
CASH FLOWS FROM DISCONTINUED OPERATIONS:
Net cash provided by (used) in discontinued operations					(1,994)	(3,438)
Effect of exchange rate changes on cash and equivalents					(1,555)	26
NET DECREASE IN CASH AND EQUIVALENTS					(4,716)	(16,375)
CASH AND EQUIVALENTS AT BEGINNING OF PERIOD		45,511		37,429	45,511	37,429
CASH AND EQUIVALENTS AT END OF PERIOD	40,795		21,054		40,795	21,054
Elimination
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	(26,804)		(29,551)		(64,236)	(63,202)
Net loss from discontinued operations			0			0
Net cash provided by (used in) operating activities:					0	0
CASH FLOWS FROM INVESTING ACTIVITIES:
Acquisition of property, plant and equipment					0	0
Acquired businesses, net of cash acquired					0	0
Investment purchase						0
Insurance payments						0
Proceeds from sale of assets					0	0
Net cash used in investing activities					0	0
CASH FLOWS FROM FINANCING ACTIVITIES:
Purchase of shares for treasury					0	0
Proceeds from long-term debt					0	0
Payments of long-term debt					0	0
Contingent consideration for acquired businesses						0
Financing costs					0	0
Dividends paid					0	0
Other, net					0	0
Net cash provided by financing activities					0	0
CASH FLOWS FROM DISCONTINUED OPERATIONS:
Net cash provided by (used) in discontinued operations					0	0
Effect of exchange rate changes on cash and equivalents					0	0
NET DECREASE IN CASH AND EQUIVALENTS					0	0
CASH AND EQUIVALENTS AT BEGINNING OF PERIOD		$ 0		$ 0	0	0
CASH AND EQUIVALENTS AT END OF PERIOD	$ 0		$ 0		$ 0	$ 0