Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Cash flows from operating activities:
Net income	$ 61,021	$ 40,496
Adjustments to reconcile net income to net cash from operating activities:
Provision for / (recovery of) credit losses on accounts receivable	(237)	722
Reserve for product returns	1,491	(105)
Recovery of credit losses on notes receivable	(368)	(3,319)
Provision for excess and obsolete inventory	1,178	15
Amortization on patents and tooling	604	506
Amortization and depreciation	20,023	15,833
Amortization of debt issuance costs	81	81
Amortization of operating leases	6,562	5,570
Deferred income taxes	(1,480)	1,502
Change in fair value of contingent liability	(2,593)	0
Stock-based compensation	20,901	14,721
Gain on notes receivable	0	(6,931)
Acquired in-process research and development	3,297	850
Gain on sale of investment	(24,737)	0
Impairment of investment	0	605
Changes in operating assets and liabilities:
Accounts receivable	(7,131)	(16,004)
Inventory	(7,209)	1,997
Other current and non-current assets	(5,549)	(3,131)
Accounts payable, accrued expenses and other current liabilities	5,897	(22,457)
Deferred revenue	2,374	(1,153)
Operating lease liabilities	(7,427)	(6,139)
Other liabilities	(28)	188
Cash flows from operating activities	66,670	23,847
Cash flows from / (used in) investing activities:
Additions to property and equipment	(10,677)	(10,660)
Purchases of in-process research and development	(3,297)	(850)
Issuances or purchases of notes receivable	(600)	(26,074)
Receipt of payment on notes receivable	2,023	31,695
Proceeds from sale of investment	25,687	0
Purchases of patents and patent licenses	(900)	0
Cash flows from / (used in) investing activities	12,236	(5,889)
Cash flows from financing activities:
Proceeds from credit facility	50,000	0
Repayments of credit facility	(2,000)	(3,000)
Payments of deferred consideration for business acquisitions	(819)	0
Purchases of treasury stock	(5,149)	0
Issuances of common stock from equity-based plans	6,609	3,304
Cash flows from financing activities	48,641	304
Net increase in cash and cash equivalents	127,547	18,262
Cash and cash equivalents at beginning of the period	119,629	146,061
Cash and cash equivalents at end of the period	$ 247,176	$ 164,323