Unaudited Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Cash flows from operating activities:
Net income	$ 12,926	$ 4,580
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Depreciation and amortization	2,411	1,604
Loss on disposal of property and equipment	34	0
Bond premium amortization	22	218
Stock-based compensation	4,093	3,447
Deferred income taxes	1,514	(1,216)
Unrecognized tax benefits	104	134
Change in assets and liabilities:
Accounts and notes receivable and contract assets	(17,060)	(11,858)
Inventory	2,408	(13,686)
Prepaid expenses and other assets	(1,702)	(2,707)
Accounts payable, accrued and other liabilities	6,749	6,562
Deferred revenue	6,554	6,313
Net cash provided by (used in) operating activities	18,053	(6,609)
Cash flows from investing activities:
Purchases of investments	(802)	0
Proceeds from maturity of investments	3,167	18,801
Purchases of property and equipment	(1,063)	(2,343)
Purchases of intangible assets	(34)	(95)
Business acquisitions	0	(6,479)
Net cash provided by investing activities	1,268	9,884
Cash flows from financing activities:
Proceeds from options exercised	356	296
Payroll tax payments for net-settled stock awards	(3,777)	(2,165)
Payments on capital lease obligation	(9)	(8)
Net cash used in financing activities	(3,430)	(1,877)
Effect of exchange rate changes on cash, cash equivalents and restricted cash	469	(76)
Net increase in cash, cash equivalents and restricted cash	16,360	1,322
Cash, cash equivalents and restricted cash, beginning of period	78,438	43,969
Cash, cash equivalents and restricted cash, end of period	94,798	45,291
Supplemental disclosure:
Cash and cash equivalents	92,330	41,974
Total cash, cash equivalents and restricted cash shown in the statements of cash flows	78,438	43,969
Cash paid for income taxes, net of refunds	63	145
Non-cash transactions
Property and equipment purchases in accounts payable and accrued liabilities	136	794
Contingent consideration related to business combinations	$ 0	$ 1,007