Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Cash flows from operating activities:
Net income	$ 5,207	$ 17,297	$ 19,933
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	8,041	3,658	3,291
Loss on disposal and abandonment of intangible assets	1,146	21	225
Purchase accounting adjustments to goodwill	(23)	520	0
(Gain) loss on disposal of property and equipment, net	(28)	42	(19)
Bond premium amortization	657	1,265	1,650
Stock-based compensation	15,610	9,369	7,263
Deferred income taxes	2,830	(5,167)	994
Unrecognized tax benefits	(191)	582	(156)
Tax benefit from stock-based compensation	0	(1,438)	(6,936)
Change in assets and liabilities:
Accounts and notes receivable	(35,305)	(28,438)	3,017
Inventory	(11,746)	(18,668)	3,140
Prepaid expenses and other assets	(9,007)	(13,928)	(7,352)
Accounts payable, accrued and other liabilities	39	17,584	5,868
Deferred revenue	39,735	34,304	15,289
Customer deposits	1,525	922	238
Net cash provided by operating activities	18,490	17,925	46,445
Cash flows from investing activities:
Purchases of investments	(19,950)	(56,086)	(62,464)
Proceeds from call / maturity of investments	61,080	64,951	44,105
Purchases of property and equipment	(10,419)	(4,957)	(6,003)
Proceeds from disposal of property and equipment	24	42	40
Purchases of intangible assets	(1,024)	(3,495)	(501)
Business acquisitions, net of cash acquired	(10,629)	(3,500)	(11,186)
Net cash provided by (used in) investing activities	19,082	(3,045)	(36,009)
Cash flows from financing activities:
Repurchase of common stock	0	(33,746)	(7,556)
Proceeds from options exercised	1,383	478	2,673
Payroll tax payments for net-settled stock awards	(3,453)	(1,772)	(1,370)
Payments on capital lease obligation	(34)	(32)	(80)
Payments on notes payable	0	(75)	0
Payment of contingent consideration for business acquisition	(1,750)	(952)	0
Excess tax benefit from stock-based compensation	0	1,438	6,936
Net cash (used in) provided by financing activities	(3,854)	(34,661)	603
Effect of exchange rate changes on cash and cash equivalents	736	906	120
Net increase (decrease) in cash and cash equivalents	34,454	(18,875)	11,159
Cash and cash equivalents, beginning of year	40,651	59,526	48,367
Cash and cash equivalents, end of year	$ 75,105	$ 40,651	$ 59,526