Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Current assets:
Cash and cash equivalents	$ 229,789	$ 193,069
Short-term marketable securities	243,505	250,378
Accounts receivable, net of allowances of $4,186 and $4,962, respectively	166,222	164,436
Inventories	253,886	237,001
Prepaid expenses and other current assets	19,587	18,417
Income taxes receivable	3,609	1,215
Total current assets	916,598	864,516
Property and equipment, net of accumulated depreciation of $313,514 and $305,575, respectively	227,541	221,076
Long-term marketable securities	546,881	562,475
Intangible assets, net	64,385	68,660
Goodwill	179,045	179,708
Other assets	34,307	36,334
Deferred income taxes	29,937	24,494
Total assets	1,998,694	1,957,263
Current liabilities:
Accounts payable	26,093	21,955
Accrued expenses	75,531	91,168
Income taxes payable	16,525	1,046
Business acquisition liabilities	11,535	11,770
Deferred revenue	11,807	12,025
Payable to broker		2,200
Total current liabilities	141,491	140,164
Business acquisition liabilities, net of current portion	56,501	58,755
Deferred income taxes	3,811	4,314
Other liabilities	11,519	12,642
Total liabilities	213,322	215,875
Commitments and contingencies (Note 15)
Equity:
Additional paid-in capital	570,082	553,787
Accumulated other comprehensive income/(loss)	(17,167)	(6,772)
Retained earnings	1,232,356	1,194,272
Total equity	1,785,372	1,741,388
Total liabilities and equity	1,998,694	1,957,263
Common Class A [Member]
Equity:
Common stock	79	79
Common Class B [Member]
Equity:
Common stock	$ 22	$ 22