Segment and Related Information - Schedule of Segment Revenues and Operations (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Segment Reporting Information [Line Items]
Total revenues	$ 221,174	$ 199,729
Operating Income	38,838	36,831
Intercompany
Segment Reporting Information [Line Items]
Total revenues	(3,237)	(2,163)
Intercompany | Enterprise Software
Segment Reporting Information [Line Items]
Total revenues	(3,237)	(2,163)
Intercompany | Appraisal and Tax
Segment Reporting Information [Line Items]
Total revenues	0	0
Corporate and Elimination
Segment Reporting Information [Line Items]
Total revenues	(2,897)	(2,163)
Operating segment and corporate non-segment
Segment Reporting Information [Line Items]
Operating Income	47,535	45,566
Operating segments | Enterprise Software
Segment Reporting Information [Line Items]
Total revenues	202,508	182,799
Operating Income	56,615	52,488
Operating segments | Appraisal and Tax
Segment Reporting Information [Line Items]
Total revenues	21,563	19,093
Operating Income	4,647	4,326
Corporate
Segment Reporting Information [Line Items]
Operating Income	(13,727)	(11,248)
Software licenses and royalties
Segment Reporting Information [Line Items]
Total revenues	22,776	21,758
Software licenses and royalties | Enterprise Software
Segment Reporting Information [Line Items]
Total revenues	20,689	20,109
Software licenses and royalties | Appraisal and Tax
Segment Reporting Information [Line Items]
Total revenues	2,087	1,649
Software licenses and royalties | Corporate
Segment Reporting Information [Line Items]
Total revenues	0	0
Subscriptions
Segment Reporting Information [Line Items]
Total revenues	49,028	39,862
Subscriptions | Enterprise Software
Segment Reporting Information [Line Items]
Total revenues	46,683	38,073
Subscriptions | Appraisal and Tax
Segment Reporting Information [Line Items]
Total revenues	2,345	1,789
Subscriptions | Corporate
Segment Reporting Information [Line Items]
Total revenues	0	0
Software services
Segment Reporting Information [Line Items]
Total revenues	45,939	42,496
Software services | Enterprise Software
Segment Reporting Information [Line Items]
Total revenues	40,286	38,146
Software services | Appraisal and Tax
Segment Reporting Information [Line Items]
Total revenues	5,653	4,350
Software services | Corporate
Segment Reporting Information [Line Items]
Total revenues	0	0
Maintenance
Segment Reporting Information [Line Items]
Total revenues	93,897	86,307
Maintenance | Enterprise Software
Segment Reporting Information [Line Items]
Total revenues	87,813	81,614
Maintenance | Appraisal and Tax
Segment Reporting Information [Line Items]
Total revenues	6,084	4,693
Maintenance | Corporate
Segment Reporting Information [Line Items]
Total revenues	0	0
Appraisal services
Segment Reporting Information [Line Items]
Total revenues	5,394	6,612
Appraisal services | Enterprise Software
Segment Reporting Information [Line Items]
Total revenues	0	0
Appraisal services | Appraisal and Tax
Segment Reporting Information [Line Items]
Total revenues	5,394	6,612
Appraisal services | Corporate
Segment Reporting Information [Line Items]
Total revenues	0	0
Hardware and other
Segment Reporting Information [Line Items]
Total revenues	4,140	2,694
Hardware and other | Enterprise Software
Segment Reporting Information [Line Items]
Total revenues	3,800	2,694
Hardware and other | Appraisal and Tax
Segment Reporting Information [Line Items]
Total revenues	0	0
Hardware and other | Corporate
Segment Reporting Information [Line Items]
Total revenues	$ 340	$ 0