Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021
Current assets:
Cash and cash equivalents	$ 150,772	$ 193,069
Short-term marketable securities	257,238	250,378
Accounts receivable, net of allowances of $4,182 and $4,962, respectively	192,814	164,436
Inventories	266,043	237,001
Prepaid expenses and other current assets	18,579	18,417
Income taxes receivable	5,722	1,215
Total current assets	891,168	864,516
Property and equipment, net of accumulated depreciation of $321,999 and $305,575, respectively	238,882	221,076
Long-term marketable securities	473,663	562,475
Intangible assets, net	59,131	68,660
Goodwill	182,702	179,708
Other assets	34,007	36,334
Deferred income taxes	35,159	24,494
Total assets	1,914,712	1,957,263
Current liabilities:
Accounts payable	34,195	21,955
Accrued expenses	82,543	91,168
Income taxes payable	3,471	1,046
Business acquisition liabilities	12,623	11,770
Deferred revenue	13,185	12,025
Payable to broker		2,200
Total current liabilities	146,017	140,164
Business acquisition liabilities, net of current portion	55,691	58,755
Deferred income taxes	2,511	4,314
Other liabilities	11,400	12,642
Total liabilities	215,619	215,875
Commitments and contingencies (Note 15)
Equity:
Additional paid-in capital	581,907	553,787
Accumulated other comprehensive income/(loss)	(25,368)	(6,772)
Retained earnings	1,142,455	1,194,272
Total equity	1,699,093	1,741,388
Total liabilities and equity	1,914,712	1,957,263
Common Class A [Member]
Equity:
Common stock	77	79
Common Class B [Member]
Equity:
Common stock	$ 22	$ 22