Consolidated Statements of Cash Flows (Unaudited) - USD ($)	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Cash flows from operating activities:
Net income (loss)	$ (8,147,000)	$ 7,198,000	$ (12,138,000)	$ 5,722,000
Adjustments to reconcile to net cash provided by operating activities:
Depreciation and amortization			17,615,000	18,777,000
Gain on sale of fixed assets			(584,000)	(239,000)
Equity-based compensation expense			4,224,000	5,094,000
Deferred income taxes			601,000	395,000
Non-cash restructuring charges			1,409,000	2,980,000
Impairment of assets held for sale	11,946,000	0	11,946,000	0
Loss on foreign currency transactions	(100,000)	500,000	701,000	824,000
Other			(190,000)	477,000
Changes in operating assets and liabilities (net of acquisitions):
Receivables net, retainage and contract assets			(289,000)	(6,007,000)
Inventories			(3,966,000)	(3,882,000)
Prepaid expenses and other assets			6,153,000	7,779,000
Accounts payable and accrued expenses			(5,887,000)	(9,960,000)
Contract liabilities			(5,056,000)	(12,616,000)
Other operating			(360,000)	853,000
Net cash provided by operating activities			14,179,000	10,197,000
Cash flows from investing activities:
Capital expenditures			(14,328,000)	(13,616,000)
Proceeds from sale of fixed assets			968,000	595,000
Patent expenditures			(197,000)	(209,000)
Other acquisition activity			0	(3,000,000)
Net cash used in investing activities			(13,557,000)	(16,230,000)
Cash flows from financing activities:
Proceeds from issuance of common stock upon stock option exercises			956,000	0
Repurchase of common stock			(25,171,000)	(18,609,000)
Distributions to non-controlling interests			(1,409,000)	0
Credit facility amendment fees			0	(1,093,000)
Payments on notes payable, net			(179,000)	(22,000)
Proceeds from line of credit, net			7,000,000	9,000,000
Principal payments on long-term debt			(13,125,000)	(13,125,000)
Net cash used in financing activities			(31,928,000)	(23,849,000)
Effect of exchange rate changes on cash			226,000	(830,000)
Net decrease in cash, cash equivalents and restricted cash for the period			(31,080,000)	(30,712,000)
Cash, cash equivalents and restricted cash, beginning of year			84,886,000	108,545,000	$ 108,545,000
Cash, cash equivalents and restricted cash, end of period	53,806,000	77,833,000	53,806,000	77,833,000	84,886,000
Cash, cash equivalents and restricted cash associated with assets held for sale, end of period	(1,709,000)	(1,641,000)	(1,709,000)	(1,641,000)
Cash, cash equivalents and restricted cash, end of period	$ 52,097,000	$ 76,192,000	$ 52,097,000	$ 76,192,000	$ 84,886,000