CONSOLIDATING GUARANTOR AND NON-GUARANTOR FINANCIAL INFORMATION (Details) - Summary of Condensed Consolidating Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2017	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Sep. 30, 2015
CURRENT ASSETS
Cash and equivalents	$ 69,448	$ 72,553	$ 68,616	$ 68,616	$ 52,001
Accounts receivable, net of allowances	227,813	233,751
Contract costs and recognized income not yet billed, net of progress payments	119,367	126,961
Inventories, net	339,393	308,869
Prepaid and other current assets	43,622	38,605
Assets of discontinued operations	479	219
Total Current Assets	800,122	780,958
PROPERTY, PLANT AND EQUIPMENT, net	410,472	405,404
GOODWILL	361,405	361,185
INTANGIBLE ASSETS, net	210,060	210,599
INTERCOMPANY RECEIVABLE	0	0
EQUITY INVESTMENTS IN SUBSIDIARIES	0	0
OTHER ASSETS	18,110	21,982
ASSETS OF DISCONTINUED OPERATIONS	4,314	1,968
Total Assets	1,804,483	1,782,096
CURRENT LIABILITIES
Notes payable and current portion of long-term debt	16,656	22,644
Accounts payable and accrued liabilities	276,442	293,935
Liabilities of discontinued operations	1,107	1,684
Total Current Liabilities	294,205	318,263
LONG-TERM DEBT, net of debt discounts	980,720	913,914
INTERCOMPANY PAYABLES	0	0
OTHER LIABILITIES	131,149	137,266
LIABILITIES OF DISCONTINUED OPERATIONS	4,321	1,706
Total Liabilities	1,410,395	1,371,149
Total Shareholders’ Equity	394,088	410,947
Total Liabilities and Shareholders’ Equity	1,804,483	1,782,096
Parent Company [Member]
CURRENT ASSETS
Cash and equivalents	21,231	6,517		22,699	2,440
Accounts receivable, net of allowances	0	0
Contract costs and recognized income not yet billed, net of progress payments	0	0
Inventories, net	0	0
Prepaid and other current assets	14,014	39,763
Assets of discontinued operations	0	0
Total Current Assets	35,245	46,280
PROPERTY, PLANT AND EQUIPMENT, net	723	956
GOODWILL	0	0
INTANGIBLE ASSETS, net	0	0
INTERCOMPANY RECEIVABLE	555,769	539,938
EQUITY INVESTMENTS IN SUBSIDIARIES	848,559	824,887
OTHER ASSETS	8,568	6,529
ASSETS OF DISCONTINUED OPERATIONS	0	0
Total Assets	1,448,864	1,418,590
CURRENT LIABILITIES
Notes payable and current portion of long-term debt	2,895	3,153
Accounts payable and accrued liabilities	28,093	65,751
Liabilities of discontinued operations	0	0
Total Current Liabilities	30,988	68,904
LONG-TERM DEBT, net of debt discounts	924,307	848,589
INTERCOMPANY PAYABLES	75,225	57,648
OTHER LIABILITIES	24,256	32,502
LIABILITIES OF DISCONTINUED OPERATIONS	0	0
Total Liabilities	1,054,776	1,007,643
Total Shareholders’ Equity	394,088	410,947
Total Liabilities and Shareholders’ Equity	1,448,864	1,418,590
Guarantor Companies [Member]
CURRENT ASSETS
Cash and equivalents	11,550	27,692		8,691	10,671
Accounts receivable, net of allowances	192,813	175,583
Contract costs and recognized income not yet billed, net of progress payments	119,114	126,961
Inventories, net	269,815	239,325
Prepaid and other current assets	16,574	31,191
Assets of discontinued operations	0	0
Total Current Assets	609,866	600,752
PROPERTY, PLANT AND EQUIPMENT, net	300,922	303,735
GOODWILL	284,875	284,875
INTANGIBLE ASSETS, net	144,620	147,960
INTERCOMPANY RECEIVABLE	756,667	713,118
EQUITY INVESTMENTS IN SUBSIDIARIES	867,153	866,595
OTHER ASSETS	5,515	12,151
ASSETS OF DISCONTINUED OPERATIONS	0	0
Total Assets	2,969,618	2,929,186
CURRENT LIABILITIES
Notes payable and current portion of long-term debt	2,358	2,307
Accounts payable and accrued liabilities	192,756	202,657
Liabilities of discontinued operations	0	0
Total Current Liabilities	195,114	204,964
LONG-TERM DEBT, net of debt discounts	17,240	18,872
INTERCOMPANY PAYABLES	768,406	737,980
OTHER LIABILITIES	100,641	114,491
LIABILITIES OF DISCONTINUED OPERATIONS	0	0
Total Liabilities	1,081,401	1,076,307
Total Shareholders’ Equity	1,888,217	1,852,879
Total Liabilities and Shareholders’ Equity	2,969,618	2,929,186
Non-Guarantor Companies [Member]
CURRENT ASSETS
Cash and equivalents	36,667	38,344		37,226	38,890
Accounts receivable, net of allowances	54,839	63,810
Contract costs and recognized income not yet billed, net of progress payments	253	0
Inventories, net	69,502	69,544
Prepaid and other current assets	12,908	16,447
Assets of discontinued operations	479	219
Total Current Assets	174,648	188,364
PROPERTY, PLANT AND EQUIPMENT, net	108,827	100,713
GOODWILL	76,530	76,310
INTANGIBLE ASSETS, net	65,440	62,639
INTERCOMPANY RECEIVABLE	356,701	307,081
EQUITY INVESTMENTS IN SUBSIDIARIES	1,062,002	1,916,622
OTHER ASSETS	4,006	12,675
ASSETS OF DISCONTINUED OPERATIONS	4,314	1,968
Total Assets	1,852,468	2,666,372
CURRENT LIABILITIES
Notes payable and current portion of long-term debt	11,403	17,184
Accounts payable and accrued liabilities	69,231	65,213
Liabilities of discontinued operations	1,107	1,684
Total Current Liabilities	81,741	84,081
LONG-TERM DEBT, net of debt discounts	39,173	46,453
INTERCOMPANY PAYABLES	795,095	735,053
OTHER LIABILITIES	12,310	26,574
LIABILITIES OF DISCONTINUED OPERATIONS	4,321	1,706
Total Liabilities	932,640	893,867
Total Shareholders’ Equity	919,828	1,772,505
Total Liabilities and Shareholders’ Equity	1,852,468	2,666,372
Elimination [Member]
CURRENT ASSETS
Cash and equivalents	0	0		$ 0	$ 0
Accounts receivable, net of allowances	(19,839)	(5,642)
Contract costs and recognized income not yet billed, net of progress payments	0	0
Inventories, net	76	0
Prepaid and other current assets	126	(48,796)
Assets of discontinued operations	0	0
Total Current Assets	(19,637)	(54,438)
PROPERTY, PLANT AND EQUIPMENT, net	0	0
GOODWILL	0	0
INTANGIBLE ASSETS, net	0	0
INTERCOMPANY RECEIVABLE	(1,669,137)	(1,560,137)
EQUITY INVESTMENTS IN SUBSIDIARIES	(2,777,714)	(3,608,104)
OTHER ASSETS	21	(9,373)
ASSETS OF DISCONTINUED OPERATIONS	0	0
Total Assets	(4,466,467)	(5,232,052)
CURRENT LIABILITIES
Notes payable and current portion of long-term debt	0	0
Accounts payable and accrued liabilities	(13,638)	(39,686)
Liabilities of discontinued operations	0	0
Total Current Liabilities	(13,638)	(39,686)
LONG-TERM DEBT, net of debt discounts	0	0
INTERCOMPANY PAYABLES	(1,638,726)	(1,530,681)
OTHER LIABILITIES	(6,058)	(36,301)
LIABILITIES OF DISCONTINUED OPERATIONS	0	0
Total Liabilities	(1,658,422)	(1,606,668)
Total Shareholders’ Equity	(2,808,045)	(3,625,384)
Total Liabilities and Shareholders’ Equity	$ (4,466,467)	$ (5,232,052)