Consolidated Statements of Stockholders' Equity - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive (Loss) Gain, net of taxes	Retained Earnings	Treasury Stock
Beginning balance (in shares) at Dec. 31, 2021		76,009
Beginning balance at Dec. 31, 2021	$ 452,677	$ 760	$ 294,124	$ 4,000	$ 183,957	$ (30,164)
Comprehensive (loss) income:
Net (loss) income	11,329				11,329
Unrealized gain (loss) on available-for-sale marketable securities, net of taxes	(5,269)			(5,269)
Total comprehensive (loss) income	6,060
Exercise of stock options and other share-based compensation, net of shares tendered for payment (in shares)		145
Exercise of stock options and other share-based compensation, net of shares tendered for payment	410	$ 2	408
Payment of statutory withholding on issuance of restricted stock units	(1,069)		(1,069)
Share-based compensation expense	2,298		2,298
Treasury shares issued for Deferred Compensation Plan, net	524		110			414
Shares issued pursuant to Employee Stock Plan	1,512		368			1,144
Dividends paid and accrued	(15,859)				(15,859)
Shares issued pursuant to Dividend Reinvestment Plan	25		6			19
Other (in shares)		4
Other	59		59
Ending balance (in shares) at Mar. 31, 2022		76,158
Ending balance at Mar. 31, 2022	446,637	$ 762	296,304	(1,269)	179,427	(28,587)
Beginning balance (in shares) at Dec. 31, 2021		76,009
Beginning balance at Dec. 31, 2021	452,677	$ 760	294,124	4,000	183,957	(30,164)
Comprehensive (loss) income:
Net (loss) income	18,471
Unrealized gain (loss) on available-for-sale marketable securities, net of taxes	(9,507)
Total comprehensive (loss) income	8,964
Ending balance (in shares) at Sep. 30, 2022		76,160
Ending balance at Sep. 30, 2022	422,076	$ 762	300,241	(5,507)	154,501	(27,921)
Beginning balance (in shares) at Mar. 31, 2022		76,158
Beginning balance at Mar. 31, 2022	446,637	$ 762	296,304	(1,269)	179,427	(28,587)
Comprehensive (loss) income:
Net (loss) income	6,820				6,820
Unrealized gain (loss) on available-for-sale marketable securities, net of taxes	(1,945)			(1,945)
Total comprehensive (loss) income	4,875
Exercise of stock options and other share-based compensation, net of shares tendered for payment (in shares)		2
Share-based compensation expense	2,292		2,292
Treasury shares issued for Deferred Compensation Plan, net	(5)		(196)			191
Dividends paid and accrued	(15,980)				(15,980)
Shares issued pursuant to Dividend Reinvestment Plan	26		5			21
Ending balance (in shares) at Jun. 30, 2022		76,160
Ending balance at Jun. 30, 2022	437,845	$ 762	298,405	(3,214)	170,267	(28,375)
Comprehensive (loss) income:
Net (loss) income	322				322
Unrealized gain (loss) on available-for-sale marketable securities, net of taxes	(2,293)			(2,293)
Total comprehensive (loss) income	(1,971)
Payment of statutory withholding on issuance of restricted stock units	(2)		(2)
Share-based compensation expense	2,271		2,271
Treasury shares issued for Deferred Compensation Plan, net	(6)		(432)			426
Dividends paid and accrued	(16,088)				(16,088)
Shares issued pursuant to Dividend Reinvestment Plan	27		(1)			28
Ending balance (in shares) at Sep. 30, 2022		76,160
Ending balance at Sep. 30, 2022	$ 422,076	$ 762	300,241	(5,507)	154,501	(27,921)
Beginning balance (in shares) at Dec. 31, 2022	74,088	76,161
Beginning balance at Dec. 31, 2022	$ 426,172	$ 762	302,304	(3,477)	154,495	(27,912)
Comprehensive (loss) income:
Net (loss) income	12,684				12,684
Unrealized gain (loss) on available-for-sale marketable securities, net of taxes	1,207			1,207
Total comprehensive (loss) income	13,891
Exercise of stock options and other share-based compensation, net of shares tendered for payment (in shares)		167
Exercise of stock options and other share-based compensation, net of shares tendered for payment	0	$ 1	(1)
Payment of statutory withholding on issuance of restricted stock units	(870)		(870)
Share-based compensation expense	1,973		1,973
Purchases of treasury stock	(2,223)					(2,223)
Treasury shares issued for Deferred Compensation Plan, net	475		307			168
Shares issued pursuant to Employee Stock Plan	1,135		(139)			1,274
Other (in shares)		1
Other	19		8		11
Ending balance (in shares) at Mar. 31, 2023		76,329
Ending balance at Mar. 31, 2023	$ 440,572	$ 763	303,582	(2,270)	167,190	(28,693)
Beginning balance (in shares) at Dec. 31, 2022	74,088	76,161
Beginning balance at Dec. 31, 2022	$ 426,172	$ 762	302,304	(3,477)	154,495	(27,912)
Comprehensive (loss) income:
Net (loss) income	15,788
Unrealized gain (loss) on available-for-sale marketable securities, net of taxes	(1,300)
Total comprehensive (loss) income	$ 14,488
Ending balance (in shares) at Sep. 30, 2023	73,849	76,329
Ending balance at Sep. 30, 2023	$ 441,733	$ 763	308,151	(4,777)	170,301	(32,705)
Beginning balance (in shares) at Mar. 31, 2023		76,329
Beginning balance at Mar. 31, 2023	440,572	$ 763	303,582	(2,270)	167,190	(28,693)
Comprehensive (loss) income:
Net (loss) income	8,598				8,598
Unrealized gain (loss) on available-for-sale marketable securities, net of taxes	(860)			(860)
Total comprehensive (loss) income	7,738
Share-based compensation expense	2,278		2,278
Treasury shares issued for Deferred Compensation Plan, net	(5)		(7)			2
Other	6				6
Ending balance (in shares) at Jun. 30, 2023		76,329
Ending balance at Jun. 30, 2023	450,589	$ 763	305,853	(3,130)	175,794	(28,691)
Comprehensive (loss) income:
Net (loss) income	(5,494)				(5,494)
Unrealized gain (loss) on available-for-sale marketable securities, net of taxes	(1,647)			(1,647)
Total comprehensive (loss) income	(7,141)
Share-based compensation expense	2,299		2,299
Purchases of treasury stock	(4,015)					(4,015)
Treasury shares issued for Deferred Compensation Plan, net	0		(1)			1
Other	$ 1				1
Ending balance (in shares) at Sep. 30, 2023	73,849	76,329
Ending balance at Sep. 30, 2023	$ 441,733	$ 763	$ 308,151	$ (4,777)	$ 170,301	$ (32,705)