CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Operating activities
Net income (loss)	$ 1,720	$ (95,695)	$ (100,639)
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Depreciation and amortization	34,020	35,312	40,974
Release of contingent consideration	(2,001)
Stock-based compensation expense	15,721	13,459	14,270
Impairment, restructuring and other non-cash charges	174	98,602	60,968
Gain on sale of equipment	(1,511)	(6,198)	(168)
Deferred income taxes	598	(4,091)	17,231
Changes in operating assets and liabilities:
Trade receivables, net	10,783	17,988	6,200
Unbilled receivables	(57,032)	(29,843)	19,912
Inventories, net	(14,054)	49,926	37,642
Prepaids and other assets	10,980	(15,084)	10,107
Accounts payable and accrued expenses	15,343	(18,755)	1,765
Other, net	(63)	(118)	(269)
Net cash provided by operating activities	14,678	45,503	107,993
Investing activities
Purchase of property, plant and equipment	(11,501)	(32,061)	(27,622)
Proceeds from sale of equipment	3,030	16,888	3,170
Acquisition of business, net of cash acquired			(20,440)
Net cash used in investing activities	(8,471)	(15,173)	(44,892)
Financing activities
Proceeds from exercise of stock options	2,181	1,616	560
ABL Credit Facility issuance costs		(815)
Repurchase of common shares	(26,570)	(100,000)
Other	(183)
Net cash provided by (used) in financing activities	(24,572)	(99,199)	560
Effect of exchange rate changes on cash activities	(789)	(6,211)	6,022
Increase (decrease) in cash and cash equivalents	(19,154)	(75,080)	69,683
Cash and cash equivalents at beginning of year	418,100	493,180	423,497
Cash and cash equivalents at end of year	$ 398,946	$ 418,100	$ 493,180