Condensed Consolidated Statements of Stockholders' Equity (Unaudited) - USD ($) $ in Thousands	Total	Common Stock [Member]	Treasury Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Other Comprehensive Loss [Member]	Retained Earnings [Member]
BALANCE at Dec. 31, 2021	$ 650,110	$ 887	$ (276,895)	$ 674,242	$ (96)	$ 251,972
BALANCE, shares at Dec. 31, 2021		88,724,000
BALANCE, shares at Dec. 31, 2021			(19,976,000)
Net income	79,912					79,912
Foreign currency translation	(383)				(383)
Unrealized gain (loss)on investments, net of tax	(5,838)				(5,838)
Treasury stock purchased	(23,117)		$ (23,117)
Treasury stock purchased, shares			(2,099,000)
Share-based compensation expense	6,234			6,234
Common stock issued	(696)	$ 7	$ (1,612)	909
Common stock issued, shares		641,000	(146,000)
BALANCE at Sep. 30, 2022	706,222	$ 894	$ (301,624)	681,385	(6,317)	331,884
BALANCE, shares at Sep. 30, 2022		89,365,000
BALANCE, shares at Sep. 30, 2022			(22,221,000)
BALANCE at Jun. 30, 2022	692,760	$ 894	$ (294,177)	679,400	(3,174)	309,817
BALANCE, shares at Jun. 30, 2022		89,359,000
BALANCE, shares at Jun. 30, 2022			(21,602,000)
Net income	22,067					22,067
Foreign currency translation	(138)				(138)
Unrealized gain (loss)on investments, net of tax	(3,005)				(3,005)
Treasury stock purchased	(7,447)		$ (7,447)
Treasury stock purchased, shares			(619,000)
Share-based compensation expense	1,918			1,918
Common stock issued	67			67
Common stock issued, shares		6,000
BALANCE at Sep. 30, 2022	706,222	$ 894	$ (301,624)	681,385	(6,317)	331,884
BALANCE, shares at Sep. 30, 2022		89,365,000
BALANCE, shares at Sep. 30, 2022			(22,221,000)
BALANCE at Dec. 31, 2022	$ 725,845	$ 894	$ (301,624)	684,183	(5,447)	347,839
BALANCE, shares at Dec. 31, 2022	89,396,192	89,396,000
BALANCE, shares at Dec. 31, 2022	(22,220,707)		(22,221,000)
Net income	$ 130,464					130,464
Foreign currency translation	(8)				(8)
Unrealized gain (loss)on investments, net of tax	456				456
Dividends to shareholders	(7,474)					(7,474)
Treasury stock purchased	(2,729)		$ (2,729)
Treasury stock purchased, shares			(221,000)
Treasury stock acquired upon sale of asset, shares			(1,800,000)
Treasury stock acquired upon sale of asset	(22,086)		$ (22,086)
Share-based compensation expense	6,651			6,651
Common stock issued	(1,460)	$ 7	$ (2,209)	742
Common stock issued, shares		680,000	(165,000)
BALANCE at Sep. 30, 2023	$ 829,659	$ 901	$ (328,648)	691,576	(4,999)	470,829
BALANCE, shares at Sep. 30, 2023	90,075,573	90,076,000
BALANCE, shares at Sep. 30, 2023	(24,406,935)		(24,407,000)
BALANCE at Jun. 30, 2023	$ 792,432	$ 900	$ (328,648)	688,805	(5,621)	436,996
BALANCE, shares at Jun. 30, 2023		90,016,000
BALANCE, shares at Jun. 30, 2023			(24,407,000)
Net income	41,307					41,307
Foreign currency translation	(31)				(31)
Unrealized gain (loss)on investments, net of tax	653				653
Dividends to shareholders	(7,474)					(7,474)
Share-based compensation expense	2,336	$ 1		2,336
Common stock issued	436			435
Common stock issued, shares		60,000
BALANCE at Sep. 30, 2023	$ 829,659	$ 901	$ (328,648)	$ 691,576	$ (4,999)	$ 470,829
BALANCE, shares at Sep. 30, 2023	90,075,573	90,076,000
BALANCE, shares at Sep. 30, 2023	(24,406,935)		(24,407,000)