Consolidated Condensed Statements of Shareholders' Equity (Unaudited) - USD ($) shares in Thousands, $ in Thousands		Total	Common Stock	Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Loss	Treasury Stock
Balance at period start (shares) at Dec. 31, 2021			31,299
Balance at period start at Dec. 31, 2021		$ 785,435	$ 313	$ 396,771	$ 496,605	$ (54,203)	$ (54,051)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock issued under employee plans		6,252		2,232			4,020
Stock-based compensation		4,463		4,463
Dividends on common stock ($0.20 per share)		(5,899)			(5,899)
Comprehensive income:
Cash flow hedging gain, net		1,082				1,082
Pension liability, net of income tax		521				521
Foreign currency translation adjustments		(163)				(163)
Net income		14,975			14,975
Comprehensive income		$ 16,415
Accounting Standards Update [Extensible Enumeration]		Accounting Standards Update 2020-06
Balance at period end (shares) at Mar. 31, 2022			31,299
Balance at period end at Mar. 31, 2022		$ 789,546	$ 313	365,555	526,472	(52,763)	(50,031)
Balance at period end (Accounting Standards Update 2020-06) at Mar. 31, 2022	[1]	(17,120)		(37,911)	20,791
Balance at period start (shares) at Dec. 31, 2022			31,299
Balance at period start at Dec. 31, 2022		745,545	$ 313	413,235	412,631	(57,858)	(22,776)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock issued under employee plans		2,600		556			2,044
Stock-based compensation		5,726		5,726
Dividends on common stock ($0.20 per share)		(6,113)			(6,113)
Comprehensive income:
Cash flow hedging gain, net		877				877
Pension liability, net of income tax		403				403
Foreign currency translation adjustments		1,596				1,596
Net income		1,819			1,819
Comprehensive income		4,695
Balance at period end (shares) at Mar. 31, 2023			31,299
Balance at period end at Mar. 31, 2023		$ 752,453	$ 313	$ 419,517	$ 408,337	$ (54,982)	$ (20,732)

[1] (1)We recorded the cumulative impact of adopting Accounting Standards Update (ASU) 2020-06, Debt—Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging—Contracts in Entity’s Own Equity (Subtopic 815-40): Accounting for Convertible Instruments and Contracts in an Entity’s Own Equity in 2022.