Unaudited Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Cash flows from operating activities:
Net income	$ 21,411	$ 6,856
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Depreciation and amortization	5,161	3,400
Loss on disposal and impairment of property and equipment, net	153	0
Loss on disposal and abandonment of intangible assets	54	0
Bond premium amortization	30	427
Stock-based compensation	9,047	7,423
Deferred income taxes	(58)	(1,458)
Unrecognized tax benefits	212	282
Change in assets and liabilities:
Accounts and notes receivable and contract assets	(24,791)	(15,925)
Inventory	4,508	(25,768)
Prepaid expenses and other assets	(7,429)	(10,055)
Accounts payable, accrued and other liabilities	(2,688)	7,531
Deferred revenue	10,496	14,829
Net cash provided by (used in) operating activities	16,106	(12,458)
Cash flows from investing activities:
Purchases of investments	(4,331)	(19,950)
Proceeds from maturity of investments	7,038	34,377
Purchases of property and equipment	(4,665)	(5,741)
Purchases of intangible assets	(254)	(170)
Business acquisitions	(5,014)	(6,479)
Net cash provided (used in) by investing activities	(7,226)	2,037
Cash flows from financing activities:
Net proceeds from equity offering	233,993	0
Proceeds from options exercised	586	1,241
Payroll tax payments for net-settled stock awards	(10,807)	(2,572)
Payment of contingent consideration for a business acquisition	(575)	0
Net cash provided by (used in) financing activities	223,197	(1,331)
Effect of exchange rate changes on cash, cash equivalents and restricted cash	(538)	(857)
Net increase (decrease) in cash, cash equivalents and restricted cash	231,539	(12,609)
Cash, cash equivalents and restricted cash, beginning of period	78,438	43,969
Cash, cash equivalents and restricted cash, end of period	309,977	31,360
Supplemental disclosures:
Cash and cash equivalents	307,507	28,038
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	7,758	9,934
Non-cash transactions
Property and equipment purchases in accounts payable and accrued liabilities	665	1,351
Non-cash purchase consideration related to business combinations	$ 12,288	$ 1,026