Segment and Related Information - Schedule of Segment Revenues and Operations (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Segment Reporting Information [Line Items]
Total revenues	$ 288,837	$ 275,400	$ 275,124	$ 247,066	$ 241,981	$ 236,067	$ 236,060	$ 221,174	$ 1,086,427	$ 935,282	$ 840,899
Depreciation and amortization expense									76,672	61,759	53,395
Total segment operating income									156,367	152,492	162,758
Capital expenditures									38,098	25,132	45,618
Total assets	2,191,614				1,790,963				2,191,614	1,790,963	1,611,351
Intercompany
Segment Reporting Information [Line Items]
Total revenues									(15,496)	(13,155)	(10,425)
Intercompany | Enterprise Software
Segment Reporting Information [Line Items]
Total revenues									(15,496)	(13,155)	(10,425)
Intercompany | Appraisal and Tax
Segment Reporting Information [Line Items]
Total revenues									0	0	0
Operating segments | Enterprise Software
Segment Reporting Information [Line Items]
Total revenues									1,000,845	853,200	765,133
Depreciation and amortization expense									64,289	50,130	43,987
Total segment operating income									261,494	237,159	229,001
Capital expenditures									19,335	13,973	28,096
Total assets	834,010				556,100				834,010	556,100	365,736
Operating segments | Appraisal and Tax
Segment Reporting Information [Line Items]
Total revenues									94,822	90,356	81,579
Depreciation and amortization expense									926	914	760
Total segment operating income									20,789	23,094	20,788
Capital expenditures									8,384	782	1,181
Total assets	90,536				63,670				90,536	63,670	46,279
Corporate and Elimination
Segment Reporting Information [Line Items]
Total revenues									(9,240)	(8,274)	(5,813)
Corporate
Segment Reporting Information [Line Items]
Depreciation and amortization expense									11,457	10,715	8,648
Total segment operating income									(73,829)	(68,572)	(51,964)
Capital expenditures									10,379	10,377	16,341
Total assets	$ 1,267,068				$ 1,171,193				1,267,068	1,171,193	1,199,336
Operating Segments And Corporate Non Segment
Segment Reporting Information [Line Items]
Total segment operating income									208,454	191,681	197,825
Software licenses and royalties
Segment Reporting Information [Line Items]
Total revenues									100,205	93,441	86,242
Software licenses and royalties | Operating segments | Enterprise Software
Segment Reporting Information [Line Items]
Total revenues									92,567	83,735	78,388
Software licenses and royalties | Operating segments | Appraisal and Tax
Segment Reporting Information [Line Items]
Total revenues									7,638	9,706	7,854
Software licenses and royalties | Corporate
Segment Reporting Information [Line Items]
Total revenues									0	0	0
Subscriptions
Segment Reporting Information [Line Items]
Total revenues									296,352	220,547	172,176
Subscriptions | Operating segments | Enterprise Software
Segment Reporting Information [Line Items]
Total revenues									285,092	210,740	164,317
Subscriptions | Operating segments | Appraisal and Tax
Segment Reporting Information [Line Items]
Total revenues									11,260	9,807	7,859
Subscriptions | Corporate
Segment Reporting Information [Line Items]
Total revenues									0	0	0
Software services
Segment Reporting Information [Line Items]
Total revenues									213,061	191,269	180,460
Software services | Operating segments | Enterprise Software
Segment Reporting Information [Line Items]
Total revenues									185,892	166,921	161,245
Software services | Operating segments | Appraisal and Tax
Segment Reporting Information [Line Items]
Total revenues									27,169	24,348	19,215
Software services | Corporate
Segment Reporting Information [Line Items]
Total revenues									0	0	0
Maintenance
Segment Reporting Information [Line Items]
Total revenues									430,318	384,521	359,319
Maintenance | Operating segments | Enterprise Software
Segment Reporting Information [Line Items]
Total revenues									405,063	359,904	337,701
Maintenance | Operating segments | Appraisal and Tax
Segment Reporting Information [Line Items]
Total revenues									25,255	24,617	21,618
Maintenance | Corporate
Segment Reporting Information [Line Items]
Total revenues									0	0	0
Appraisal services
Segment Reporting Information [Line Items]
Total revenues									23,479	21,846	25,023
Appraisal services | Operating segments | Enterprise Software
Segment Reporting Information [Line Items]
Total revenues									0	0	0
Appraisal services | Operating segments | Appraisal and Tax
Segment Reporting Information [Line Items]
Total revenues									23,479	21,846	25,023
Appraisal services | Corporate
Segment Reporting Information [Line Items]
Total revenues									0	0	0
Hardware and other
Segment Reporting Information [Line Items]
Total revenues									23,012	23,658	17,679
Hardware and other | Operating segments | Enterprise Software
Segment Reporting Information [Line Items]
Total revenues									16,735	18,745	13,057
Hardware and other | Operating segments | Appraisal and Tax
Segment Reporting Information [Line Items]
Total revenues									21	32	10
Hardware and other | Corporate
Segment Reporting Information [Line Items]
Total revenues									$ 6,256	$ 4,881	$ 4,612