SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Change in Accounting (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Jan. 01, 2018	Dec. 31, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Unbilled Contracts Receivable	$ 65,326	$ 38,951	$ 37,785
Inventories, net	25,606	24,045	24,337
Prepaid Expense, Current	2,403	1,863	2,266
Accrued Liabilities, Current	18,469	17,911	17,862
Deferred Revenue, Current	5,516	7,833	6,090
Deferred Tax Liabilities, Net, Noncurrent	16,290	19,042	19,367
Retained Earnings (Accumulated Deficit)	(131,221)	(116,429)	(115,433)
Calculated under Revenue Guidance in Effect before Topic 606 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Unbilled Contracts Receivable	64,371		37,785
Inventories, net	26,273		24,337
Prepaid Expense, Current			2,266
Accrued Liabilities, Current	18,426		17,862
Deferred Revenue, Current	5,613		6,090
Deferred Tax Liabilities, Net, Noncurrent	16,327		19,367
Retained Earnings (Accumulated Deficit)	$ (131,600)		$ (115,433)
Difference between Revenue Guidance in Effect before and after Topic 606 [Member] | Accounting Standards Update 2014-09
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Unbilled Contracts Receivable		1,166
Inventories, net		(292)
Prepaid Expense, Current		(403)
Accrued Liabilities, Current		49
Deferred Revenue, Current		1,743
Deferred Tax Liabilities, Net, Noncurrent		(325)
Retained Earnings (Accumulated Deficit)		$ (996)