SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Reclassifications for Accounting Pronouncements (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Jan. 01, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Retained earnings	$ 1,944,324	$ 1,754,907
Recoverable costs and estimated earnings not billed	160,727	149,847
Inventories, net	378,866	366,974
Income Tax Expense (Benefit)	84,728	$ 78,579	$ 82,946
Accounting Standards Update 2016-09 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Income Tax Expense (Benefit)	$ (8,000)
Subsequent Event [Member] | Accounting Standards Update 2014-09 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Retained earnings				$ (2,000)
Recoverable costs and estimated earnings not billed				18,000
Inventories, net				$ (24,000)