Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Cash flows from / (used in) operating activities:
Net income	$ 8,571	$ 9,010
Adjustments to reconcile net income to net cash from / (used in) operating activities:
Provision for credit losses on accounts receivable	1,885	260
Reserve for product returns	291	(120)
Provision for credit losses on notes receivable	(349)	0
Amortization on patents and tooling	199	167
Amortization and depreciation	6,422	5,228
Amortization of debt issuance costs	27	27
Amortization of operating leases	2,045	1,803
Deferred income taxes	1,327	135
Change in fair value of contingent liability	(568)	0
Stock-based compensation	6,358	4,266
Acquired in-process research and development	3,297	0
Changes in operating assets and liabilities:
Accounts receivable	(8,064)	(6,753)
Inventory	(2,673)	(2,724)
Other current and non-current assets	(6,108)	(909)
Accounts payable, accrued expenses and other current liabilities	83	(9,987)
Deferred revenue	1,604	360
Operating lease liabilities	(2,259)	(1,908)
Other liabilities	812	(42)
Cash flows from / (used in) operating activities	12,900	(1,187)
Cash flows used in investing activities:
Additions to property and equipment	(3,719)	(2,962)
Purchases of in-process research and development	(3,297)	0
Issuances or purchases of notes receivable	0	(20,061)
Receipt of payment on notes receivable	3	0
Cash flows used in investing activities	(7,013)	(23,023)
Cash flows from financing activities:
Proceeds from credit facility	50,000	0
Repayments of credit facility	0	(1,000)
Purchases of treasury stock	(5,149)	0
Issuances of common stock from equity-based plans	1,365	1,591
Cash flows from financing activities	46,216	591
Net increase / (decrease) in cash and cash equivalents	52,103	(23,619)
Cash and cash equivalents at beginning of the period	119,629	146,061
Cash and cash equivalents at end of the period	$ 171,732	$ 122,442