Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Cash flows from operating activities:
Net income	$ 29,205	$ 5,207	$ 17,297
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	10,615	8,041	3,658
Loss on disposal and abandonment of intangible assets	2,117	1,146	21
Purchase accounting adjustments to goodwill	0	(23)	520
Loss (gain) on disposal and impairment of property and equipment, net	303	(28)	42
Bond premium amortization	34	657	1,265
Stock-based compensation	21,879	15,610	9,369
Deferred income taxes	(3,592)	2,830	(5,167)
Unrecognized tax benefits	1,144	(191)	582
Tax benefit from stock-based compensation	0	0	(1,438)
Change in assets and liabilities:
Accounts and notes receivable	(67,643)	(35,305)	(28,438)
Inventory	14,804	(11,746)	(18,668)
Prepaid expenses and other assets	(12,739)	(8,992)	(10,611)
Accounts payable, accrued and other liabilities	13,506	1,530	18,399
Deferred revenue	54,242	39,735	34,304
Net cash provided by operating activities	63,875	18,471	21,135
Cash flows from investing activities:
Purchases of investments	(4,331)	(19,950)	(56,086)
Proceeds from call / maturity of investments	11,158	61,080	64,951
Purchases of property and equipment	(11,139)	(10,419)	(4,957)
Proceeds from disposal of property and equipment	0	24	42
Purchases of intangible assets	(558)	(1,024)	(3,495)
Business acquisitions, net of cash acquired	(4,990)	(10,629)	(3,500)
Net cash provided by (used in) investing activities	(9,860)	19,082	(3,045)
Cash flows from financing activities:
Net proceeds from equity offering	233,993	0	0
Repurchase of common stock	0	0	(33,746)
Proceeds from options exercised	1,757	1,383	478
Income and payroll tax payments for net-settled stock awards	(14,127)	(3,453)	(1,772)
Payment of contingent consideration for business acquisitions	(2,275)	(1,750)	(952)
Excess tax benefit from stock-based compensation	0	0	1,438
Net cash provided by (used in) financing activities	219,348	(3,820)	(34,554)
Effect of exchange rate changes on cash and cash equivalents	(774)	737	906
Net increase (decrease) in cash and cash equivalents	272,589	34,470	(15,558)
Cash and cash equivalents and restricted cash, beginning of year	78,438	43,968	59,526
Cash and cash equivalents and restricted cash, end of year	$ 349,462	$ 75,105	$ 40,651