REVENUE - Cumulative Effective of Adoption of ASC 606 (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Mar. 31, 2019	Dec. 31, 2018	Oct. 01, 2018	Sep. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017
CURRENT ASSETS
Contract costs and recognized income not yet billed, net of progress payments	$ 90,825		$ 90,825				$ 100,821	$ 121,803
Inventories	436,885		436,885				420,384	398,359
Total Current Assets	961,353		961,353				913,917	912,874
Total Assets	2,111,459		2,111,459				2,085,933	2,084,890
CURRENT LIABILITIES
Accounts payable	205,570		205,570				241,940	233,658
Billings in excess of costs	24,470		24,470				25,841
Total Current Liabilities	367,230		367,230				401,353	393,071
OTHER LIABILITIES	94,148		94,148				105,144	106,710
Total Liabilities	1,623,294		1,623,294				1,617,215	1,610,499
SHAREHOLDERS’ EQUITY
Retained Earnings	555,780		555,780				544,850
Total Shareholders' Equity	488,165	$ 466,087	488,165	$ 466,087	$ 474,284	$ 471,561	468,718	474,391	$ 474,018	$ 434,813	$ 398,808
Total Liabilities and Shareholders’ Equity	2,111,459		2,111,459				2,085,933	2,084,890
Income Statement
Net sales	574,970	516,550	1,635,125	1,432,413
Cost of goods and services	420,487	377,868	1,200,092	1,051,573
Income (loss) before taxes from continuing operations	20,386	9,002	44,035	10,117
Provision (benefit) from income taxes	6,258	1,560	14,664	(22,107)
Income from continuing operations	14,128	$ 7,442	29,371	$ 32,224
Calculated under Revenue Guidance in Effect before Topic 606 [Member]
CURRENT ASSETS
Contract costs and recognized income not yet billed, net of progress payments	108,926		108,926					121,803
Inventories	416,315		416,315					398,359
Total Current Assets	958,884		958,884					912,874
Total Assets	2,108,990		2,108,990					2,084,890
CURRENT LIABILITIES
Accounts payable	197,288		197,288					233,658
Billings in excess of costs	16,188		16,188					17,559
Total Current Liabilities	358,948		358,948					393,071
OTHER LIABILITIES	95,403		95,403					106,710
Total Liabilities	1,616,267		1,616,267					1,610,499
SHAREHOLDERS’ EQUITY
Retained Earnings	560,338		560,338					550,523
Total Shareholders' Equity	492,723		492,723					474,391
Total Liabilities and Shareholders’ Equity	2,108,990		2,108,990					$ 2,084,890
Income Statement
Net sales	578,276		1,632,245
Cost of goods and services	423,529		1,198,638
Income (loss) before taxes from continuing operations	20,649		42,609
Provision (benefit) from income taxes	6,316		14,353
Income from continuing operations	14,334		28,256
Difference between Revenue Guidance in Effect before and after Topic 606 [Member] | Accounting Standards Update 2014-09 (ASC 606) [Member]
CURRENT ASSETS
Contract costs and recognized income not yet billed, net of progress payments	(18,101)		(18,101)				(20,982)
Inventories	20,570		20,570				22,025
Total Current Assets	2,469		2,469				1,043
Total Assets	2,469		2,469				1,043
CURRENT LIABILITIES
Accounts payable	8,282		8,282				8,282
Billings in excess of costs	8,282		8,282				8,282
Total Current Liabilities	8,282		8,282				8,282
OTHER LIABILITIES	(1,255)		(1,255)				(1,566)
Total Liabilities	7,027		7,027				6,716
SHAREHOLDERS’ EQUITY
Retained Earnings	(4,558)		(4,558)				(5,673)
Total Shareholders' Equity	(4,558)		(4,558)				(5,673)
Total Liabilities and Shareholders’ Equity	2,469		2,469				$ 1,043
Income Statement
Net sales	(3,306)		2,880
Cost of goods and services	(3,042)		1,454
Income (loss) before taxes from continuing operations	(263)		1,426
Provision (benefit) from income taxes	(58)		311
Income from continuing operations	$ (206)		$ 1,115