CONSOLIDATING GUARANTOR AND NON-GUARANTOR FINANCIAL INFORMATION (Details) - Summary of Condensed Consolidating Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2018	Oct. 01, 2018	Sep. 30, 2018	Dec. 31, 2017	Sep. 30, 2017
CURRENT ASSETS
Cash and equivalents	$ 81,752		$ 69,758	$ 84,420	$ 47,681
Accounts receivable, net of allowances	253,351		280,509
Contract costs and recognized income not yet billed, net of progress payments	89,232	$ 100,821	121,803
Inventories	452,362	420,384	398,359
Prepaid and other current assets	39,615		42,121
Assets of discontinued operations	325		324
Total Current Assets	916,637	913,917	912,874
PROPERTY, PLANT AND EQUIPMENT, net	336,490		342,492
GOODWILL	438,428		439,395
INTANGIBLE ASSETS, net	365,381		370,858
INTERCOMPANY RECEIVABLE	0		0
EQUITY INVESTMENTS IN SUBSIDIARIES	0		0
OTHER ASSETS	14,944		16,355
ASSETS OF DISCONTINUED OPERATIONS	2,909		2,916
Total Assets	2,074,789	2,085,933	2,084,890
CURRENT LIABILITIES
Notes payable and current portion of long-term debt	12,872		13,011
Accounts payable and accrued liabilities	347,570		372,850
Liabilities of discontinued operations	6,882		7,210
Total Current Liabilities	367,324	401,353	393,071
LONG-TERM DEBT, net of debt discounts	1,142,079		1,108,071
INTERCOMPANY PAYABLES	0		0
OTHER LIABILITIES	91,315	105,144	106,710
LIABILITIES OF DISCONTINUED OPERATIONS	2,510		2,647
Total Liabilities	1,603,228	1,617,215	1,610,499
Total Shareholders’ Equity	471,561	468,718	474,391
Total Liabilities and Shareholders’ Equity	2,074,789	$ 2,085,933	2,084,890
Parent Company [Member]
CURRENT ASSETS
Cash and equivalents	10,629		15,976	5,931	3,240
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	8,067		12,179
Assets of discontinued operations	0		0
Total Current Assets	18,696		28,155
PROPERTY, PLANT AND EQUIPMENT, net	887		936
GOODWILL	0		6,646
INTANGIBLE ASSETS, net	93		93
INTERCOMPANY RECEIVABLE	67,780		56,396
EQUITY INVESTMENTS IN SUBSIDIARIES	1,542,276		1,528,932
OTHER ASSETS	6,708		8,651
ASSETS OF DISCONTINUED OPERATIONS	0		0
Total Assets	1,636,440		1,629,809
CURRENT LIABILITIES
Notes payable and current portion of long-term debt	2,276		2,276
Accounts payable and accrued liabilities	27,556		26,639
Liabilities of discontinued operations	0		0
Total Current Liabilities	29,832		28,915
LONG-TERM DEBT, net of debt discounts	1,077,036		1,044,071
INTERCOMPANY PAYABLES	51,497		66,058
OTHER LIABILITIES	6,514		16,374
LIABILITIES OF DISCONTINUED OPERATIONS	0		0
Total Liabilities	1,164,879		1,155,418
Total Shareholders’ Equity	471,561		474,391
Total Liabilities and Shareholders’ Equity	1,636,440		1,629,809
Guarantor Companies [Member]
CURRENT ASSETS
Cash and equivalents	32,096		16,353	31,437	8,066
Accounts receivable, net of allowances	217,290		234,885
Contract costs and recognized income not yet billed, net of progress payments	88,019		121,393
Inventories	384,893		332,067
Prepaid and other current assets	22,507		21,313
Assets of discontinued operations	0		0
Total Current Assets	744,805		726,011
PROPERTY, PLANT AND EQUIPMENT, net	295,409		299,920
GOODWILL	394,008		361,507
INTANGIBLE ASSETS, net	279,849		293,093
INTERCOMPANY RECEIVABLE	621,995		314,394
EQUITY INVESTMENTS IN SUBSIDIARIES	508,267		968,330
OTHER ASSETS	17,057		15,942
ASSETS OF DISCONTINUED OPERATIONS	0		0
Total Assets	2,861,390		2,979,197
CURRENT LIABILITIES
Notes payable and current portion of long-term debt	3,448		3,398
Accounts payable and accrued liabilities	280,395		303,154
Liabilities of discontinued operations	0		(22,327)
Total Current Liabilities	283,843		284,225
LONG-TERM DEBT, net of debt discounts	5,250		6,110
INTERCOMPANY PAYABLES	283,010		(77,760)
OTHER LIABILITIES	71,569		73,391
LIABILITIES OF DISCONTINUED OPERATIONS	0		0
Total Liabilities	643,672		285,966
Total Shareholders’ Equity	2,217,718		2,693,231
Total Liabilities and Shareholders’ Equity	2,861,390		2,979,197
Non-Guarantor Companies [Member]
CURRENT ASSETS
Cash and equivalents	39,027		37,429	47,052	36,375
Accounts receivable, net of allowances	36,535		69,729
Contract costs and recognized income not yet billed, net of progress payments	1,213		410
Inventories	67,462		66,373
Prepaid and other current assets	6,668		6,168
Assets of discontinued operations	325		324
Total Current Assets	151,230		180,433
PROPERTY, PLANT AND EQUIPMENT, net	40,194		41,636
GOODWILL	44,420		71,242
INTANGIBLE ASSETS, net	85,439		77,672
INTERCOMPANY RECEIVABLE	58,690		(121,445)
EQUITY INVESTMENTS IN SUBSIDIARIES	3,029,840		3,347,894
OTHER ASSETS	(2,136)		374
ASSETS OF DISCONTINUED OPERATIONS	2,909		2,916
Total Assets	3,410,586		3,600,722
CURRENT LIABILITIES
Notes payable and current portion of long-term debt	7,148		7,337
Accounts payable and accrued liabilities	32,424		59,531
Liabilities of discontinued operations	6,882		29,537
Total Current Liabilities	46,454		96,405
LONG-TERM DEBT, net of debt discounts	59,793		57,890
INTERCOMPANY PAYABLES	415,912		263,227
OTHER LIABILITIES	16,882		20,592
LIABILITIES OF DISCONTINUED OPERATIONS	2,510		2,647
Total Liabilities	541,551		440,761
Total Shareholders’ Equity	2,869,035		3,159,961
Total Liabilities and Shareholders’ Equity	3,410,586		3,600,722
Elimination [Member]
CURRENT ASSETS
Cash and equivalents	0		0	$ 0	$ 0
Accounts receivable, net of allowances	(474)		(24,105)
Contract costs and recognized income not yet billed, net of progress payments	0		0
Inventories	7		(81)
Prepaid and other current assets	2,373		2,461
Assets of discontinued operations	0		0
Total Current Assets	1,906		(21,725)
PROPERTY, PLANT AND EQUIPMENT, net	0		0
GOODWILL	0		0
INTANGIBLE ASSETS, net	0		0
INTERCOMPANY RECEIVABLE	(748,465)		(249,345)
EQUITY INVESTMENTS IN SUBSIDIARIES	(5,080,383)		(5,845,156)
OTHER ASSETS	(6,685)		(8,612)
ASSETS OF DISCONTINUED OPERATIONS	0		0
Total Assets	(5,833,627)		(6,124,838)
CURRENT LIABILITIES
Notes payable and current portion of long-term debt	0		0
Accounts payable and accrued liabilities	7,195		(16,474)
Liabilities of discontinued operations	0		0
Total Current Liabilities	7,195		(16,474)
LONG-TERM DEBT, net of debt discounts	0		0
INTERCOMPANY PAYABLES	(750,419)		(251,525)
OTHER LIABILITIES	(3,650)		(3,647)
LIABILITIES OF DISCONTINUED OPERATIONS	0		0
Total Liabilities	(746,874)		(271,646)
Total Shareholders’ Equity	(5,086,753)		(5,853,192)
Total Liabilities and Shareholders’ Equity	$ (5,833,627)		$ (6,124,838)