Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Statement of Financial Position [Abstract]
Trade accounts receivable, allowances for doubtful accounts	$ 6,640	$ 6,824
Patents, trademarks, and other intangible assets, accumulated amortization	$ 68,520	$ 66,078
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized	250,000,000	250,000,000
Common stock, shares issued	129,729,406	128,930,047
Treasury stock, shares held	3,133,674	2,953,976