Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Net Cash Provided by (Used in) Operating Activities [Abstract]
Net income	$ 61,338	$ 37,729	$ 30,518
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	53,559	51,350	51,511
Loss on disposal of property and equipment	445	133	512
Share-based compensation expense	34,049	28,885	21,857
Income tax benefits from employee stock plans	0	0	11
Deferred income taxes	(1,339)	(5,705)	(31,365)
Amortization of operating lease right-of-use assets	10,562	0	0
Amortization of debt issuance costs	2,204	2,292	1,590
Changes in operating assets and liabilities:
Accounts receivable and unbilled receivables	(21,540)	(6,192)	(40,598)
Inventories	(8,123)	(6,763)	(26,840)
Prepaid expenses	2,909	(308)	(4,920)
Other current assets	(2,010)	1,170	(2,074)
Investment in sales-type leases	(3,699)	(1,680)	6,625
Prepaid commissions	(2,719)	(4,711)	(3,966)
Other long-term assets	4,528	(7,077)	(1,373)
Accounts payable	7,893	(9,154)	19,709
Accrued compensation	2,495	14,419	519
Accrued liabilities	3,045	8,223	4,383
Deferred revenues	5,445	3,020	(2,334)
Operating lease liabilities	(10,040)	0	0
Other long-term liabilities	6,006	(1,665)	1,069
Net cash provided by operating activities	145,008	103,966	24,834
Investing Activities
Purchase of intangible assets, intellectual property, and patents	0	0	(160)
Software development for external use	(45,770)	(30,677)	(15,040)
Purchases of property and equipment	(15,894)	(23,697)	(15,341)
Business acquisitions, net of cash acquired	0	0	(4,446)
Net cash used in investing activities	(61,664)	(54,374)	(34,987)
Financing Activities
Proceeds from Issuance of Debt	0	0	59,000
Repayment of debt and revolving credit facility	(90,000)	(77,000)	(102,500)
Payments for debt issuance costs	(2,321)	0	(2,106)
Payment for contingent consideration	0	0	(2,400)
At the market offering, net of offering costs	37,806	39,567	13,900
Proceeds from issuances under stock-based compensation plans	40,706	30,611	30,121
Employees’ taxes paid related to restricted stock units	(9,670)	(6,775)	(5,892)
Net cash used in financing activities	(23,479)	(13,597)	(9,877)
Effect of exchange rate changes on cash and cash equivalents	153	(1,227)	(2,034)
Net increase (decrease) in cash and cash equivalents	60,018	34,768	(22,064)
Cash and cash equivalents at beginning of period	67,192	32,424	54,488
Cash and cash equivalents at end of period	127,210	67,192	32,424
Supplemental cash flow information
Cash paid for interest	3,582	7,487	6,550
Cash paid for taxes, net of refunds	7,761	3,489	7,780
Supplemental disclosure of non-cash activities
Non-cash activity business acquisition	0	0	3,400
Unpaid purchases of property and equipment	913	1,123	1,691
Transfers between inventory and property and equipment, net	1,552	2,032	0
Transfers from prepaid expenses to property and equipment	3,313	0	0
Right-of-use assets obtained in exchange for new lease liabilities	1,204	0	0
Balance transfer from term loan to revolving credit facility	$ 80,000	$ 0	$ 0