Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Operating Activities
Net income	$ 208,737	$ 175,631	$ 144,738
Adjustments to reconcile net income to net cash provided by operating activities:
Goodwill impairment losses	54,245	0	0
Depreciation and amortization	35,946	17,939	14,031
Deferred income taxes	21,012	13,125	7,706
Stock-based compensation	8,438	7,131	6,930
(Gain) loss on disposal of property, plant and equipment	(45)	(56)	285
Other non-cash adjustments	40	51	(218)
Changes in operating assets and liabilities:
Accounts receivable	(44,349)	(28,286)	12,701
Inventories	(15,515)	(12,132)	1,695
Prepaid expenses and other assets	(8,715)	(358)	(1,652)
Accounts payable	(3,473)	11,353	(16,666)
Accrued expenses and other liabilities	(5,285)	7,655	(10,823)
Income taxes receivable/payable	7,028	(4,759)	(2,375)
Net cash provided by operating activities	258,064	187,294	156,352
Investing Activities
Expenditures for property, plant and equipment and intangibles	(159,394)	(172,823)	(67,265)
Proceeds from sales of property, plant and equipment	1,355	2,165	21
Net cash used in investing activities	(158,039)	(170,658)	(67,244)
Financing Activities
Borrowings under line of credit	494,500	276,000	89,500
Principal payments under line of credit	(494,500)	(276,000)	(89,500)
Repurchases of common stock	(82,473)	(44,854)	(46,545)
Proceeds from employee stock purchase and option plans	1,800	1,446	1,089
Financing costs		(360)	(518)
Net cash used in financing activities	(80,673)	(43,768)	(45,974)
Net increase (decrease) in cash and cash equivalents	19,352	(27,132)	43,134
Cash and cash equivalents at beginning of year	121,701	148,833	105,699
Cash and cash equivalents at end of year	141,053	121,701	148,833
Supplemental disclosures of cash flow information:
Cash paid for interest, net of capitalized interest	0	0	0
Cash paid for income taxes, net	$ 38,614	$ 50,744	$ 39,612