Segment and Related Information - Schedule of Segment Revenues and Operations (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Segment Reporting Information
Total revenues	$ 285,746	$ 275,400	$ 833,378	$ 797,590
Segment operating income	49,656	40,053	124,890	111,210
Intercompany
Segment Reporting Information
Total revenues	(5,166)	(4,029)	(13,720)	(11,242)
Intercompany | Enterprise Software
Segment Reporting Information
Total revenues	5,128	3,995	13,662	11,055
Intercompany | Appraisal and Tax
Segment Reporting Information
Total revenues	38	34	58	187
Operating segments | Enterprise Software
Segment Reporting Information
Total revenues	261,939	246,940	759,995	709,030
Segment operating income	79,911	62,539	209,408	177,681
Operating segments | Appraisal and Tax
Segment Reporting Information
Total revenues	28,973	32,503	87,101	93,666
Segment operating income	8,318	9,178	21,374	24,196
Corporate
Segment Reporting Information
Total revenues	(5,166)	(4,043)	(13,718)	(5,106)
Segment operating income	(25,216)	(18,043)	(65,718)	(52,260)
Operating segment and corporate non-segment
Segment Reporting Information
Segment operating income	63,013	53,674	165,064	149,617
Software licenses and royalties
Segment Reporting Information
Total revenues	19,937	25,379	55,699	67,847
Software licenses and royalties | Enterprise Software
Segment Reporting Information
Total revenues	17,798	22,954	48,432	59,031
Software licenses and royalties | Appraisal and Tax
Segment Reporting Information
Total revenues	2,139	2,425	7,267	8,816
Software licenses and royalties | Corporate
Segment Reporting Information
Total revenues	0	0	0	0
Subscriptions
Segment Reporting Information
Total revenues	89,290	75,272	256,651	216,022
Subscriptions | Enterprise Software
Segment Reporting Information
Total revenues	82,972	70,833	238,744	203,474
Subscriptions | Appraisal and Tax
Segment Reporting Information
Total revenues	6,318	4,439	17,907	12,548
Subscriptions | Corporate
Segment Reporting Information
Total revenues	0	0	0	0
Software services
Segment Reporting Information
Total revenues	47,946	54,997	143,733	160,841
Software services | Enterprise Software
Segment Reporting Information
Total revenues	42,640	44,752	126,488	133,612
Software services | Appraisal and Tax
Segment Reporting Information
Total revenues	5,306	10,245	17,245	27,229
Software services | Corporate
Segment Reporting Information
Total revenues	0	0	0	0
Maintenance
Segment Reporting Information
Total revenues	117,979	109,833	349,104	316,674
Maintenance | Enterprise Software
Segment Reporting Information
Total revenues	108,270	100,519	320,447	289,348
Maintenance | Appraisal and Tax
Segment Reporting Information
Total revenues	9,709	9,314	28,657	27,326
Maintenance | Corporate
Segment Reporting Information
Total revenues	0	0	0	0
Appraisal services
Segment Reporting Information
Total revenues	5,394	6,008	15,853	17,455
Appraisal services | Enterprise Software
Segment Reporting Information
Total revenues	0	0	0	0
Appraisal services | Appraisal and Tax
Segment Reporting Information
Total revenues	5,394	6,008	15,853	17,455
Appraisal services | Corporate
Segment Reporting Information
Total revenues	0	0	0	0
Hardware and other
Segment Reporting Information
Total revenues	5,200	3,911	12,338	18,751
Hardware and other | Enterprise Software
Segment Reporting Information
Total revenues	5,131	3,887	12,222	12,510
Hardware and other | Appraisal and Tax
Segment Reporting Information
Total revenues	69	38	114	105
Hardware and other | Corporate
Segment Reporting Information
Total revenues	$ 0	$ (14)	$ 2	$ 6,136