Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Statement of Financial Position [Abstract]
Trade accounts receivable, allowances for doubtful accounts	$ 414	$ 6,824
Patents, trademarks, and other intangible assets, accumulated amortization	$ 69,186	$ 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	130,075,838	128,930,047
Treasury stock, shares held	3,135,434	2,953,976