Segment and Related Information - Schedule of Segment Revenues and Operations (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Segment Reporting Information [Line Items]
Revenue	$ 247,066	$ 221,174
Operating income	34,491	38,838
Operating segments | Enterprise Software
Segment Reporting Information [Line Items]
Revenue	227,375	202,508
Operating income	57,034	56,615
Operating segments | Appraisal and Tax
Segment Reporting Information [Line Items]
Revenue	23,247	21,563
Operating income	5,535	4,647
Intercompany | Enterprise Software
Segment Reporting Information [Line Items]
Revenue	3,553	3,237
Intercompany | Appraisal and Tax
Segment Reporting Information [Line Items]
Revenue	0	0
Intercompany | Corporate
Segment Reporting Information [Line Items]
Revenue	(3,553)	(3,237)
Corporate
Segment Reporting Information [Line Items]
Operating income	(16,546)	(13,727)
Operating segment and corporate non-segment
Segment Reporting Information [Line Items]
Operating income	46,023	47,535
Software licenses and royalties
Segment Reporting Information [Line Items]
Revenue	21,793	22,776
Software licenses and royalties | Enterprise Software
Segment Reporting Information [Line Items]
Revenue	19,011	20,689
Software licenses and royalties | Appraisal and Tax
Segment Reporting Information [Line Items]
Revenue	2,782	2,087
Software licenses and royalties | Corporate
Segment Reporting Information [Line Items]
Revenue	0	0
Subscriptions
Segment Reporting Information [Line Items]
Revenue	67,275	49,028
Subscriptions | Enterprise Software
Segment Reporting Information [Line Items]
Revenue	64,642	46,683
Subscriptions | Appraisal and Tax
Segment Reporting Information [Line Items]
Revenue	2,633	2,345
Subscriptions | Corporate
Segment Reporting Information [Line Items]
Revenue	0	0
Software services
Segment Reporting Information [Line Items]
Revenue	48,443	45,939
Software services | Enterprise Software
Segment Reporting Information [Line Items]
Revenue	41,967	40,286
Software services | Appraisal and Tax
Segment Reporting Information [Line Items]
Revenue	6,476	5,653
Software services | Corporate
Segment Reporting Information [Line Items]
Revenue	0	0
Maintenance
Segment Reporting Information [Line Items]
Revenue	100,152	93,897
Maintenance | Enterprise Software
Segment Reporting Information [Line Items]
Revenue	94,012	87,813
Maintenance | Appraisal and Tax
Segment Reporting Information [Line Items]
Revenue	6,140	6,084
Maintenance | Corporate
Segment Reporting Information [Line Items]
Revenue	0	0
Appraisal services
Segment Reporting Information [Line Items]
Revenue	5,214	5,394
Appraisal services | Enterprise Software
Segment Reporting Information [Line Items]
Revenue	0	0
Appraisal services | Appraisal and Tax
Segment Reporting Information [Line Items]
Revenue	5,214	5,394
Appraisal services | Corporate
Segment Reporting Information [Line Items]
Revenue	0	0
Hardware and other
Segment Reporting Information [Line Items]
Revenue	4,189	4,140
Hardware and other | Enterprise Software
Segment Reporting Information [Line Items]
Revenue	4,190	3,800
Hardware and other | Appraisal and Tax
Segment Reporting Information [Line Items]
Revenue	2	0
Hardware and other | Corporate
Segment Reporting Information [Line Items]
Revenue	$ (3)	$ 340