Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Statement of Cash Flows [Abstract]
Net income	$ 105,925	$ 113,876
Adjustments to reconcile net income to net cash provided by operating activities:
Gain on sale of assets and other	(263)	(1,716)
Depreciation and amortization	29,044	29,049
Noncash lease expense	5,278
Deferred income taxes and other long-term liabilities	2,262	2,061
Noncash compensation related to stock plans	8,699	8,773
Provision of doubtful accounts	435	361
Foreign exchange gain on capital repatriation	0	(1,604)
Changes in operating assets and liabilities, net of acquisitions:
Trade accounts receivable	(36,385)	(58,678)
Inventories	31,163	(29,233)
Trade accounts payable	8,130	14,254
Other current assets	(3,197)	5,099
Accrued liabilities and other current liabilities	3,452	26,356
Other noncurrent assets and liabilities	(5,308)	(629)
Net cash provided by operating activities	149,235	107,969
Cash flows from investing activities
Capital expenditures	(24,495)	(24,714)
Asset acquisitions, net of cash acquired	(3,529)	0
Proceeds from sale of property and equipment	2,498	3,539
Net cash used in investing activities	(25,526)	(21,175)
Cash flows from financing activities
Repurchase of common stock	(51,437)	(49,490)
Proceeds from line of credit	13,308	0
Repayments of line of credit and capital leases	(14,335)	(702)
Issuance of common stock for exercise of options	0	695
Dividends paid	(30,002)	(29,738)
Cash paid on behalf of employees for shares withheld	(5,905)	(5,128)
Net cash used in financing activities	(88,371)	(84,363)
Effect of exchange rate changes on cash and cash equivalents	(1,457)	(3,984)
Net increase (decrease) in cash and cash equivalents	33,881	(1,553)
Cash and cash equivalents at beginning of period	160,180	168,514
Cash and cash equivalents at end of period	194,061	166,961
Noncash activity during the period
Noncash capital expenditures	194	212
Dividends declared but not paid	10,162	10,134
Issuance of Company’s common stock for compensation	$ 292	$ 465