Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Disaggregation of Revenue [Line Items]
Revenue	$ 247,066	$ 221,174
Operating segments | Enterprise Software
Disaggregation of Revenue [Line Items]
Revenue	227,375	202,508
Operating segments | Appraisal and Tax
Disaggregation of Revenue [Line Items]
Revenue	23,247	21,563
Intercompany | Enterprise Software
Disaggregation of Revenue [Line Items]
Revenue	3,553	3,237
Intercompany | Appraisal and Tax
Disaggregation of Revenue [Line Items]
Revenue	0	0
Intercompany | Corporate
Disaggregation of Revenue [Line Items]
Revenue	(3,553)	(3,237)
Corporate and Elimination
Disaggregation of Revenue [Line Items]
Revenue	(3,556)	(2,897)
Corporate and Elimination | Corporate
Disaggregation of Revenue [Line Items]
Revenue	(3,556)	(2,897)
Recurring revenues
Disaggregation of Revenue [Line Items]
Revenue	167,427	142,925
Recurring revenues | Enterprise Software
Disaggregation of Revenue [Line Items]
Revenue	158,654	134,496
Recurring revenues | Appraisal and Tax
Disaggregation of Revenue [Line Items]
Revenue	8,773	8,429
Recurring revenues | Corporate
Disaggregation of Revenue [Line Items]
Revenue	0	0
Non-recurring revenues
Disaggregation of Revenue [Line Items]
Revenue	79,639	78,249
Non-recurring revenues | Enterprise Software
Disaggregation of Revenue [Line Items]
Revenue	65,168	64,775
Non-recurring revenues | Appraisal and Tax
Disaggregation of Revenue [Line Items]
Revenue	14,474	13,134
Non-recurring revenues | Corporate
Disaggregation of Revenue [Line Items]
Revenue	(3)	340
Software licenses and royalties
Disaggregation of Revenue [Line Items]
Revenue	21,793	22,776
Software licenses and royalties | Enterprise Software
Disaggregation of Revenue [Line Items]
Revenue	19,011	20,689
Software licenses and royalties | Appraisal and Tax
Disaggregation of Revenue [Line Items]
Revenue	2,782	2,087
Software licenses and royalties | Corporate
Disaggregation of Revenue [Line Items]
Revenue	0	0
Subscriptions
Disaggregation of Revenue [Line Items]
Revenue	67,275	49,028
Subscriptions | Enterprise Software
Disaggregation of Revenue [Line Items]
Revenue	64,642	46,683
Subscriptions | Appraisal and Tax
Disaggregation of Revenue [Line Items]
Revenue	2,633	2,345
Subscriptions | Corporate
Disaggregation of Revenue [Line Items]
Revenue	0	0
Software services
Disaggregation of Revenue [Line Items]
Revenue	48,443	45,939
Software services | Enterprise Software
Disaggregation of Revenue [Line Items]
Revenue	41,967	40,286
Software services | Appraisal and Tax
Disaggregation of Revenue [Line Items]
Revenue	6,476	5,653
Software services | Corporate
Disaggregation of Revenue [Line Items]
Revenue	0	0
Maintenance
Disaggregation of Revenue [Line Items]
Revenue	100,152	93,897
Maintenance | Enterprise Software
Disaggregation of Revenue [Line Items]
Revenue	94,012	87,813
Maintenance | Appraisal and Tax
Disaggregation of Revenue [Line Items]
Revenue	6,140	6,084
Maintenance | Corporate
Disaggregation of Revenue [Line Items]
Revenue	0	0
Appraisal services
Disaggregation of Revenue [Line Items]
Revenue	5,214	5,394
Appraisal services | Enterprise Software
Disaggregation of Revenue [Line Items]
Revenue	0	0
Appraisal services | Appraisal and Tax
Disaggregation of Revenue [Line Items]
Revenue	5,214	5,394
Appraisal services | Corporate
Disaggregation of Revenue [Line Items]
Revenue	0	0
Hardware and other
Disaggregation of Revenue [Line Items]
Revenue	4,189	4,140
Hardware and other | Enterprise Software
Disaggregation of Revenue [Line Items]
Revenue	4,190	3,800
Hardware and other | Appraisal and Tax
Disaggregation of Revenue [Line Items]
Revenue	2	0
Hardware and other | Corporate
Disaggregation of Revenue [Line Items]
Revenue	(3)	340
Products and services transferred at a point in time
Disaggregation of Revenue [Line Items]
Revenue	21,099	23,203
Products and services transferred at a point in time | Software licenses and royalties
Disaggregation of Revenue [Line Items]
Revenue	16,910	19,063
Products and services transferred at a point in time | Subscriptions
Disaggregation of Revenue [Line Items]
Revenue	0	0
Products and services transferred at a point in time | Software services
Disaggregation of Revenue [Line Items]
Revenue	0	0
Products and services transferred at a point in time | Maintenance
Disaggregation of Revenue [Line Items]
Revenue	0	0
Products and services transferred at a point in time | Appraisal services
Disaggregation of Revenue [Line Items]
Revenue	0	0
Products and services transferred at a point in time | Hardware and other
Disaggregation of Revenue [Line Items]
Revenue	4,189	4,140
Products and services transferred over time
Disaggregation of Revenue [Line Items]
Revenue	225,967	197,971
Products and services transferred over time | Software licenses and royalties
Disaggregation of Revenue [Line Items]
Revenue	4,883	3,713
Products and services transferred over time | Subscriptions
Disaggregation of Revenue [Line Items]
Revenue	67,275	49,028
Products and services transferred over time | Software services
Disaggregation of Revenue [Line Items]
Revenue	48,443	45,939
Products and services transferred over time | Maintenance
Disaggregation of Revenue [Line Items]
Revenue	100,152	93,897
Products and services transferred over time | Appraisal services
Disaggregation of Revenue [Line Items]
Revenue	5,214	5,394
Products and services transferred over time | Hardware and other
Disaggregation of Revenue [Line Items]
Revenue	$ 0	$ 0
Minimum
Disaggregation of Revenue [Line Items]
Contract term	1 year
Typical contract term	3 years
Minimum | Appraisal services
Disaggregation of Revenue [Line Items]
Contract term	1 year
Maximum
Disaggregation of Revenue [Line Items]
Contract term	10 years
Typical contract term	5 years
Maximum | Appraisal services
Disaggregation of Revenue [Line Items]
Contract term	3 years