Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Cash flows from operating activities
Net income	$ 13,915	$ 9,506
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Depreciation and amortization	1,448	1,177
Deferred taxes	2,451	(22)
Stock-based compensation expense	1,132	1,075
Provision for excess and obsolete inventory	485	578
Changes in operating assets & liabilities:
Accounts receivable	16	(16,178)
Inventories	(11,462)	(844)
Prepaid expenses and other current assets	592	(2,347)
Accounts payable and other current liabilities	(1,836)	3,049
Deferred revenue	1,963	2,085
Income taxes	113	2
Other assets and liabilities	(317)	(749)
Net cash provided by (used in) operating activities	8,500	(2,668)
Cash flows from investing activities
Expenditures for property, plant and equipment and capitalized software	(723)	(1,116)
Net cash used in investing activities	(723)	(1,116)
Cash flows from financing activities
Net settlement on restricted stock grants	(226)	(286)
Proceeds from exercise of stock options	446	2,531
Net cash provided by financing activities	220	2,245
Effect of exchange rate changes on cash and cash equivalents	(406)	105
Net increase (decrease) in cash, cash equivalents and restricted cash	7,591	(1,434)
Cash, cash equivalents and restricted cash at beginning of period		140,880
Cash, cash equivalents and restricted cash at end of period	$ 148,471	$ 76,221