CONSOLIDATING GUARANTOR AND NON-GUARANTOR FINANCIAL INFORMATION (Details) - Summary of Condensed Consolidating Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Oct. 01, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017
CURRENT ASSETS
Cash and equivalents	$ 58,112				$ 69,758	$ 63,766			$ 47,681
Accounts receivable, net of allowances	322,310				280,509
Contract costs and recognized income not yet billed, net of progress payments	90,825			$ 100,821	121,803
Inventories	436,885			420,384	398,359
Prepaid and other current assets	52,898				42,121
Assets of discontinued operations	323				324
Total Current Assets	961,353			913,917	912,874
PROPERTY, PLANT AND EQUIPMENT, net	331,345				342,492
GOODWILL	438,417				439,395
INTANGIBLE ASSETS, net	361,249				370,858
INTERCOMPANY RECEIVABLE	0				0
EQUITY INVESTMENTS IN SUBSIDIARIES	0				0
OTHER ASSETS	16,200				16,355
ASSETS OF DISCONTINUED OPERATIONS	2,895				2,916
Total Assets	2,111,459			2,085,933	2,084,890
CURRENT LIABILITIES
Notes payable and current portion of long-term debt	10,884				13,011
Accounts payable and accrued liabilities	353,693				372,850
Liabilities of discontinued operations	2,653				7,210
Total Current Liabilities	367,230			401,353	393,071
LONG-TERM DEBT, net of debt discounts	1,159,621				1,108,071
INTERCOMPANY PAYABLES	0				0
OTHER LIABILITIES	94,148			105,144	106,710
LIABILITIES OF DISCONTINUED OPERATIONS	2,295				2,647
Total Liabilities	1,623,294			1,617,215	1,610,499
Total Shareholders’ Equity	488,165	$ 474,284	$ 471,561	468,718	474,391	466,087	$ 474,018	$ 434,813	398,808
Total Liabilities and Shareholders’ Equity	2,111,459			$ 2,085,933	2,084,890
Parent Company [Member]
CURRENT ASSETS
Cash and equivalents	15,350				15,976	8,589			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	19,961				12,179
Assets of discontinued operations	0				0
Total Current Assets	35,311				28,155
PROPERTY, PLANT AND EQUIPMENT, net	966				936
GOODWILL	0				6,646
INTANGIBLE ASSETS, net	93				93
INTERCOMPANY RECEIVABLE	110,797				56,396
EQUITY INVESTMENTS IN SUBSIDIARIES	1,575,766				1,528,932
OTHER ASSETS	7,389				8,651
ASSETS OF DISCONTINUED OPERATIONS	0				0
Total Assets	1,730,322				1,629,809
CURRENT LIABILITIES
Notes payable and current portion of long-term debt	0				2,276
Accounts payable and accrued liabilities	59,575				26,639
Liabilities of discontinued operations	0				0
Total Current Liabilities	59,575				28,915
LONG-TERM DEBT, net of debt discounts	1,112,182				1,044,071
INTERCOMPANY PAYABLES	58,361				66,058
OTHER LIABILITIES	12,039				16,374
LIABILITIES OF DISCONTINUED OPERATIONS	0				0
Total Liabilities	1,242,157				1,155,418
Total Shareholders’ Equity	488,165				474,391
Total Liabilities and Shareholders’ Equity	1,730,322				1,629,809
Guarantor Companies [Member]
CURRENT ASSETS
Cash and equivalents	20,477				16,353	18,470			8,066
Accounts receivable, net of allowances	267,210				234,885
Contract costs and recognized income not yet billed, net of progress payments	89,862				121,393
Inventories	371,592				332,067
Prepaid and other current assets	23,583				21,313
Assets of discontinued operations	0				0
Total Current Assets	772,724				726,011
PROPERTY, PLANT AND EQUIPMENT, net	290,869				299,920
GOODWILL	394,131				361,507
INTANGIBLE ASSETS, net	276,252				293,093
INTERCOMPANY RECEIVABLE	914,366				314,394
EQUITY INVESTMENTS IN SUBSIDIARIES	523,262				968,330
OTHER ASSETS	17,495				15,942
ASSETS OF DISCONTINUED OPERATIONS	0				0
Total Assets	3,189,099				2,979,197
CURRENT LIABILITIES
Notes payable and current portion of long-term debt	3,547				3,398
Accounts payable and accrued liabilities	246,990				303,154
Liabilities of discontinued operations	0				(22,327)
Total Current Liabilities	250,537				284,225
LONG-TERM DEBT, net of debt discounts	3,491				6,110
INTERCOMPANY PAYABLES	615,658				(77,760)
OTHER LIABILITIES	68,312				73,391
LIABILITIES OF DISCONTINUED OPERATIONS	0				0
Total Liabilities	937,998				285,966
Total Shareholders’ Equity	2,251,101				2,693,231
Total Liabilities and Shareholders’ Equity	3,189,099				2,979,197
Non-Guarantor Companies [Member]
CURRENT ASSETS
Cash and equivalents	22,285				37,429	36,707			36,375
Accounts receivable, net of allowances	55,100				69,729
Contract costs and recognized income not yet billed, net of progress payments	963				410
Inventories	65,560				66,373
Prepaid and other current assets	6,970				6,168
Assets of discontinued operations	323				324
Total Current Assets	151,201				180,433
PROPERTY, PLANT AND EQUIPMENT, net	39,510				41,636
GOODWILL	44,286				71,242
INTANGIBLE ASSETS, net	84,904				77,672
INTERCOMPANY RECEIVABLE	65,131				(121,445)
EQUITY INVESTMENTS IN SUBSIDIARIES	3,063,638				3,347,894
OTHER ASSETS	(2,157)				374
ASSETS OF DISCONTINUED OPERATIONS	2,895				2,916
Total Assets	3,449,408				3,600,722
CURRENT LIABILITIES
Notes payable and current portion of long-term debt	7,337				7,337
Accounts payable and accrued liabilities	46,162				59,531
Liabilities of discontinued operations	2,653				29,537
Total Current Liabilities	56,152				96,405
LONG-TERM DEBT, net of debt discounts	43,948				57,890
INTERCOMPANY PAYABLES	422,227				263,227
OTHER LIABILITIES	11,389				20,592
LIABILITIES OF DISCONTINUED OPERATIONS	2,295				2,647
Total Liabilities	536,011				440,761
Total Shareholders’ Equity	2,913,397				3,159,961
Total Liabilities and Shareholders’ Equity	3,449,408				3,600,722
Elimination [Member]
CURRENT ASSETS
Cash and equivalents	0				0	$ 0			$ 0
Accounts receivable, net of allowances	0				(24,105)
Contract costs and recognized income not yet billed, net of progress payments	0				0
Inventories	(267)				(81)
Prepaid and other current assets	2,384				2,461
Assets of discontinued operations	0				0
Total Current Assets	2,117				(21,725)
PROPERTY, PLANT AND EQUIPMENT, net	0				0
GOODWILL	0				0
INTANGIBLE ASSETS, net	0				0
INTERCOMPANY RECEIVABLE	(1,090,294)				(249,345)
EQUITY INVESTMENTS IN SUBSIDIARIES	(5,162,666)				(5,845,156)
OTHER ASSETS	(6,527)				(8,612)
ASSETS OF DISCONTINUED OPERATIONS	0				0
Total Assets	(6,257,370)				(6,124,838)
CURRENT LIABILITIES
Notes payable and current portion of long-term debt	0				0
Accounts payable and accrued liabilities	966				(16,474)
Liabilities of discontinued operations	0				0
Total Current Liabilities	966				(16,474)
LONG-TERM DEBT, net of debt discounts	0				0
INTERCOMPANY PAYABLES	(1,096,246)				(251,525)
OTHER LIABILITIES	2,408				(3,647)
LIABILITIES OF DISCONTINUED OPERATIONS	0				0
Total Liabilities	(1,092,872)				(271,646)
Total Shareholders’ Equity	(5,164,498)				(5,853,192)
Total Liabilities and Shareholders’ Equity	$ (6,257,370)				$ (6,124,838)