CONSOLIDATING GUARANTOR AND NON-GUARANTOR FINANCIAL INFORMATION (Details) - Summary of consolidated balance sheets - USD ($) $ in Thousands	Sep. 30, 2019	Oct. 01, 2018	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2016
CURRENT ASSETS
Cash and equivalents	$ 72,377		$ 69,758	$ 47,681	$ 72,553
Accounts receivable, net of allowances	264,450		280,509
Contract costs and recognized income not yet billed, net of progress payments	105,111		121,803
Inventories	442,121	$ 420,384	398,359
Prepaid and other current assets	40,799		42,121
Assets of discontinued operations	321		324
Total Current Assets	925,179	913,917	912,874
PROPERTY, PLANT AND EQUIPMENT, net	337,326		342,492
GOODWILL	437,067		439,395	319,139
INTANGIBLE ASSETS, net	356,639		370,858
INTERCOMPANY RECEIVABLE	0		0
EQUITY INVESTMENTS IN SUBSIDIARIES	0		0
OTHER ASSETS	15,840		16,355
ASSETS OF DISCONTINUED OPERATIONS	2,888		2,916
Total Assets	2,074,939	2,085,933	2,084,890	1,873,541
CURRENT LIABILITIES
Notes payable and current portion of long-term debt	10,525		13,011
Accounts payable and accrued liabilities	375,241		372,850
Liabilities of discontinued operations	4,333		7,210
Total Current Liabilities	390,099	401,353	393,071
LONG-TERM DEBT, net of debt discounts	1,093,749		1,108,071
INTERCOMPANY PAYABLES	0		0
OTHER LIABILITIES	109,997	105,089	106,710
LIABILITIES OF DISCONTINUED OPERATIONS	3,331		2,647
Total Liabilities	1,597,176	1,617,160	1,610,499
SHAREHOLDERS’ EQUITY	477,763	468,773	474,391	398,808	410,947
Total Liabilities and Shareholders’ Equity	2,074,939	$ 2,085,933	2,084,890
Parent Company [Member]
CURRENT ASSETS
Cash and equivalents	1,649		15,976	3,240	6,517
Accounts receivable, net of allowances	0		0
Contract costs and recognized income not yet billed, net of progress payments	0		0
Inventories	0		0
Prepaid and other current assets	8,238		12,179
Assets of discontinued operations	0		0
Total Current Assets	9,887		28,155
PROPERTY, PLANT AND EQUIPMENT, net	1,184		936
GOODWILL	0		6,646
INTANGIBLE ASSETS, net	93		93
INTERCOMPANY RECEIVABLE	5,834		56,396
EQUITY INVESTMENTS IN SUBSIDIARIES	1,628,031		1,528,932
OTHER ASSETS	8,182		8,651
ASSETS OF DISCONTINUED OPERATIONS	0		0
Total Assets	1,653,211		1,629,809
CURRENT LIABILITIES
Notes payable and current portion of long-term debt	0		2,276
Accounts payable and accrued liabilities	41,796		26,639
Liabilities of discontinued operations	0		0
Total Current Liabilities	41,796		28,915
LONG-TERM DEBT, net of debt discounts	1,040,449		1,044,071
INTERCOMPANY PAYABLES	71,634		66,058
OTHER LIABILITIES	21,569		16,374
LIABILITIES OF DISCONTINUED OPERATIONS	0		0
Total Liabilities	1,175,448		1,155,418
SHAREHOLDERS’ EQUITY	477,763		474,391
Total Liabilities and Shareholders’ Equity	1,653,211		1,629,809
Guarantor Subsidiaries [Member]
CURRENT ASSETS
Cash and equivalents	25,217		16,353	8,066	27,692
Accounts receivable, net of allowances	227,069		234,885
Contract costs and recognized income not yet billed, net of progress payments	104,109		121,393
Inventories	372,839		332,067
Prepaid and other current assets	25,754		21,313
Assets of discontinued operations	0		0
Total Current Assets	754,988		726,011
PROPERTY, PLANT AND EQUIPMENT, net	289,282		299,920
GOODWILL	375,734		361,507
INTANGIBLE ASSETS, net	224,275		293,093
INTERCOMPANY RECEIVABLE	864,884		314,394
EQUITY INVESTMENTS IN SUBSIDIARIES	581,438		968,330
OTHER ASSETS	24,635		15,942
ASSETS OF DISCONTINUED OPERATIONS	0		0
Total Assets	3,115,236		2,979,197
CURRENT LIABILITIES
Notes payable and current portion of long-term debt	3,075		3,398
Accounts payable and accrued liabilities	266,411		303,154
Liabilities of discontinued operations	0		(22,327)
Total Current Liabilities	269,486		284,225
LONG-TERM DEBT, net of debt discounts	3,119		6,110
INTERCOMPANY PAYABLES	457,265		(77,760)
OTHER LIABILITIES	81,582		73,391
LIABILITIES OF DISCONTINUED OPERATIONS	0		0
Total Liabilities	811,452		285,966
SHAREHOLDERS’ EQUITY	2,303,784		2,693,231
Total Liabilities and Shareholders’ Equity	3,115,236		2,979,197
Non-Guarantor Subsidiaries [Member]
CURRENT ASSETS
Cash and equivalents	45,511		37,429	36,375	38,344
Accounts receivable, net of allowances	38,580		69,729
Contract costs and recognized income not yet billed, net of progress payments	1,002		410
Inventories	69,540		66,373
Prepaid and other current assets	6,951		6,168
Assets of discontinued operations	321		324
Total Current Assets	161,905		180,433
PROPERTY, PLANT AND EQUIPMENT, net	46,860		41,636
GOODWILL	61,333		71,242
INTANGIBLE ASSETS, net	132,271		77,672
INTERCOMPANY RECEIVABLE	75,684		(121,445)
EQUITY INVESTMENTS IN SUBSIDIARIES	3,233,038		3,347,894
OTHER ASSETS	(2,352)		374
ASSETS OF DISCONTINUED OPERATIONS	2,888		2,916
Total Assets	3,711,627		3,600,722
CURRENT LIABILITIES
Notes payable and current portion of long-term debt	7,450		7,337
Accounts payable and accrued liabilities	68,390		59,531
Liabilities of discontinued operations	4,333		29,537
Total Current Liabilities	80,173		96,405
LONG-TERM DEBT, net of debt discounts	50,181		57,890
INTERCOMPANY PAYABLES	444,557		263,227
OTHER LIABILITIES	15,017		20,592
LIABILITIES OF DISCONTINUED OPERATIONS	3,331		2,647
Total Liabilities	593,259		440,761
SHAREHOLDERS’ EQUITY	3,118,368		3,159,961
Total Liabilities and Shareholders’ Equity	3,711,627		3,600,722
Consolidation, Eliminations [Member]
CURRENT ASSETS
Cash and equivalents	0		0	$ 0	$ 0
Accounts receivable, net of allowances	(1,199)		(24,105)
Contract costs and recognized income not yet billed, net of progress payments	0		0
Inventories	(258)		(81)
Prepaid and other current assets	(144)		2,461
Assets of discontinued operations	0		0
Total Current Assets	(1,601)		(21,725)
PROPERTY, PLANT AND EQUIPMENT, net	0		0
GOODWILL	0		0
INTANGIBLE ASSETS, net	0		0
INTERCOMPANY RECEIVABLE	(946,402)		(249,345)
EQUITY INVESTMENTS IN SUBSIDIARIES	(5,442,507)		(5,845,156)
OTHER ASSETS	(14,625)		(8,612)
ASSETS OF DISCONTINUED OPERATIONS	0		0
Total Assets	(6,405,135)		(6,124,838)
CURRENT LIABILITIES
Notes payable and current portion of long-term debt	0		0
Accounts payable and accrued liabilities	(1,356)		(16,474)
Liabilities of discontinued operations	0		0
Total Current Liabilities	(1,356)		(16,474)
LONG-TERM DEBT, net of debt discounts	0		0
INTERCOMPANY PAYABLES	(973,456)		(251,525)
OTHER LIABILITIES	(8,171)		(3,647)
LIABILITIES OF DISCONTINUED OPERATIONS	0		0
Total Liabilities	(982,983)		(271,646)
SHAREHOLDERS’ EQUITY	(5,422,152)		(5,853,192)
Total Liabilities and Shareholders’ Equity	$ (6,405,135)		$ (6,124,838)