Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Cash flows from operating activities:
Net income	$ 91,206	$ 62,191
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	24,203	23,023
Non-cash deferred revenue	(1,116)	(4,991)
Increase in inventory reserve	5,687	3,217
Unrealized gain on investment in equity securities	(10,757)
Unrealized gain on foreign currency contracts	(1,582)
Stock based compensation	4,106	6,321
Deferred income tax provision	(14,025)	1,087
Other	(146)	516
Changes in assets and liabilities:
Account receivables	12,144	35,995
Contract assets	(58,147)
Inventories	1,747	(38,245)
Prepaid expenses and other current assets	6,446	(70)
Accounts payable and other current liabilities	(17,476)	(16,422)
Contract liabilities, current	471	512
Other non-current assets and liabilities	(3,338)	(2,282)
Discontinued operations:
Non-current liabilities	898	2,418
Net cash used in discontinued operations	(557)	(1,185)
Net cash provided by operating activities	39,764	72,085
Cash flows from investing activities:
Capital expenditures	(43,545)	(38,241)
Proceeds from sale of business		2,836
Acquisition of business, net of cash acquired	(418,963)
Net cash used in investing activities	(462,508)	(35,405)
Cash flows from financing activities:
Borrowings	325,000
Proceeds from stock options exercised	12,685	3,448
Net cash provided by financing activities	337,685	3,448
Effect of exchange rate changes on cash and cash equivalents	(1,090)	4,134
Net (decrease)/increase in cash and cash equivalents	(86,149)	44,262
Cash and cash equivalents at beginning of period	183,284	74,141
Cash and cash equivalents at end of period	$ 97,135	$ 118,403