CONSOLIDATED STATEMENTS OF INCOME - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Income Statement [Abstract]
Revenues		$ 352,664	$ 331,168	$ 322,559
Cost of revenues	[1]	58,000	53,379	49,990
Gross profit		294,664	277,789	272,569
Operating expenses:
Sales and marketing	[1]	53,648	47,116	51,522
Research, development and engineering	[1]	7,652	7,146	9,745
General and administrative	[1]	58,228	26,852	21,475
Total operating expenses		119,528	81,114	82,742
Income from operations		175,136	196,675	189,827
Interest expense		(14,272)	(75,788)	(43,457)
Interest income		60	0	797
Other income (expense), net		160	31,569	(1,421)
Income before income taxes		161,084	152,456	145,746
Income tax expense (benefit)		39,910	30,043	(33,137)
Income from continuing operations		121,174	122,413	178,883
(Loss) income from discontinued operations, net of income tax	[1]	(12,173)	30,500	34,084
Net income		$ 109,001	$ 152,913	$ 212,967
Net income per common share from continuing operations:
Basic (in dollars per share)		$ 6.07	$ 6.15	$ 8.99
Diluted (in dollars per share)		6.04	6.15	8.99
Net (loss) income per common share from discontinued operations:
Basic (in dollars per share)		(0.61)	1.53	1.71
Diluted (in dollars per share)		(0.61)	1.53	1.71
Net income per common share
Basic (in dollars per share)		5.46	7.68	10.70
Diluted (in dollars per share)		$ 5.44	$ 7.68	$ 10.70
Weighted average shares outstanding:
Basic (in shares)		19,904,237	19,902,924	19,902,924
Diluted (in shares)		19,986,889	19,902,924	19,902,924

[1] (1) Includes share-based compensation expense as follows: Cost of revenues$72 $203 $466 Sales and marketing92 442 134 Research, development and engineering(19)383 501 General and administrative1,711 457 (16)(Loss) income from discontinued operations602 4,138 2,711 Total$2,458 $5,623 $3,796