Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Operating Activities
Net income	$ 109,241	$ 109,401
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	10,477	13,164
Stock-based compensation	5,844	5,045
Loss (gain) on disposal of property, plant and equipment	90	50
Other non-cash adjustments	(372)	(408)
Changes in operating assets and liabilities:
Accounts receivable	(26,225)	(21,034)
Inventories	13,878	(927)
Prepaid expenses and other assets	2,129	(3,155)
Accounts payable	(6,443)	8,245
Accrued expenses and other liabilities	(10,262)	619
Income taxes receivable/payable	629	4,369
Net cash provided by operating activities	98,986	115,369
Investing Activities
Expenditures for property, plant and equipment and intangibles	(36,926)	(21,611)
Proceeds from sales of property, plant and equipment	21	83
Net cash used in investing activities	(36,905)	(21,528)
Financing Activities
Borrowings under line of credit	89,500	172,250
Principal payments under line of credit	(89,500)	(172,250)
Repurchases of common stock	(35,216)	(17,723)
Proceeds from employee stock purchase and option plans	718	681
Net cash used in financing activities	(34,498)	(17,042)
Net increase in cash and cash equivalents	27,583	76,799
Cash and cash equivalents, beginning of period	105,699	30,514
Cash and cash equivalents, end of period	133,282	107,313
Supplemental Disclosure:
Cash paid for interest	321	662
Cash paid for income taxes, net	$ 32,872	$ 39,170