REVENUE, Cumulative Effect of Changes made to Consolidated Balance Sheet (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Balance Sheet [Abstract]
Unbilled receivables	$ 16,553	$ 0
Inventory	114,434	107,719
Other current liabilities	3,836	6,204
Retained earnings	165,518	147,807
ASU 2014-09 [Member]
Balance Sheet [Abstract]
Unbilled receivables		14,536
Inventory		96,675
Other current liabilities		6,247
Retained earnings		151,256
Adjustments Due to ASC 606 [Member] \| ASU 2014-09 [Member]
Balance Sheet [Abstract]
Unbilled receivables	16,553	14,536
Inventory	(12,303)	(11,044)
Other current liabilities	121	43
Retained earnings	4,129	$ 3,449
Balances Without Adoption of ASC 606 [Member] \| ASU 2014-09 [Member]
Balance Sheet [Abstract]
Unbilled receivables	0
Inventory	126,737
Other current liabilities	3,715
Retained earnings	$ 161,389

Amount, after allowance for credit loss, of right to consideration in exchange for good or service transferred to customer when right is conditioned on something other than passage of time, classified as current.

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Amount after valuation and LIFO reserves of inventory expected to be sold, or consumed within one year or operating cycle, if longer.

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Amount of liabilities classified as other, due within one year or the normal operating cycle, if longer.

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The cumulative amount of the reporting entity's undistributed earnings or deficit.

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