Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Disaggregation of Revenue
Total revenues	$ 271,091	$ 275,124	$ 547,632	$ 522,190
Operating segments | Enterprise Software
Disaggregation of Revenue
Total revenues	247,879	241,055	498,056	462,090
Operating segments | Appraisal and Tax
Disaggregation of Revenue
Total revenues	27,747	31,576	58,128	61,163
Intercompany
Disaggregation of Revenue
Total revenues	(4,535)	(3,660)	(8,554)	(7,213)
Intercompany | Enterprise Software
Disaggregation of Revenue
Total revenues	4,533	3,576	8,534	7,060
Intercompany | Appraisal and Tax
Disaggregation of Revenue
Total revenues	2	84	20	153
Corporate
Disaggregation of Revenue
Total revenues	(4,535)	2,493	(8,552)	(1,063)
Corporate and Elimination
Disaggregation of Revenue
Total revenues	(4,535)	2,493	(8,552)	(1,063)
Operating segment and corporate non-segment
Disaggregation of Revenue
Total revenues				0
Recurring revenues
Disaggregation of Revenue
Total revenues	202,398	180,164	398,486	347,591
Recurring revenues | Enterprise Software
Disaggregation of Revenue
Total revenues	186,464	167,027	367,949	321,470
Recurring revenues | Appraisal and Tax
Disaggregation of Revenue
Total revenues	15,934	13,137	30,537	26,121
Recurring revenues | Corporate
Disaggregation of Revenue
Total revenues	0	0	0	0
Non-recurring revenues
Disaggregation of Revenue
Total revenues	68,693	94,960	149,146	174,599
Non-recurring revenues | Enterprise Software
Disaggregation of Revenue
Total revenues	56,882	70,452	121,573	133,560
Non-recurring revenues | Appraisal and Tax
Disaggregation of Revenue
Total revenues	11,811	18,355	27,571	34,889
Non-recurring revenues | Corporate
Disaggregation of Revenue
Total revenues	0	6,153	2	6,150
Software licenses and royalties
Disaggregation of Revenue
Total revenues	17,025	20,675	35,762	42,468
Software licenses and royalties | Enterprise Software
Disaggregation of Revenue
Total revenues	14,683	17,555	30,634	36,077
Software licenses and royalties | Appraisal and Tax
Disaggregation of Revenue
Total revenues	2,342	3,120	5,128	6,391
Software licenses and royalties | Corporate
Disaggregation of Revenue
Total revenues	0	0	0	0
Subscriptions
Disaggregation of Revenue
Total revenues	85,638	73,475	167,361	140,750
Subscriptions | Enterprise Software
Disaggregation of Revenue
Total revenues	79,128	69,386	155,772	132,641
Subscriptions | Appraisal and Tax
Disaggregation of Revenue
Total revenues	6,510	4,089	11,589	8,109
Subscriptions | Corporate
Disaggregation of Revenue
Total revenues	0	0	0	0
Software services
Disaggregation of Revenue
Total revenues	43,654	57,401	95,787	105,844
Software services | Enterprise Software
Disaggregation of Revenue
Total revenues	38,899	48,404	83,848	88,860
Software services | Appraisal and Tax
Disaggregation of Revenue
Total revenues	4,755	8,997	11,939	16,984
Software services | Corporate
Disaggregation of Revenue
Total revenues	0	0	0	0
Maintenance
Disaggregation of Revenue
Total revenues	116,760	106,689	231,125	206,841
Maintenance | Enterprise Software
Disaggregation of Revenue
Total revenues	107,336	97,641	212,177	188,829
Maintenance | Appraisal and Tax
Disaggregation of Revenue
Total revenues	9,424	9,048	18,948	18,012
Maintenance | Corporate
Disaggregation of Revenue
Total revenues	0	0	0	0
Appraisal services
Disaggregation of Revenue
Total revenues	4,696	6,233	10,459	11,447
Appraisal services | Enterprise Software
Disaggregation of Revenue
Total revenues	0	0	0	0
Appraisal services | Appraisal and Tax
Disaggregation of Revenue
Total revenues	4,696	6,233	10,459	11,447
Appraisal services | Corporate
Disaggregation of Revenue
Total revenues	0	0	0	0
Hardware and other
Disaggregation of Revenue
Total revenues	3,318	10,651	7,138	14,840
Hardware and other | Enterprise Software
Disaggregation of Revenue
Total revenues	3,300	4,493	7,091	8,623
Hardware and other | Appraisal and Tax
Disaggregation of Revenue
Total revenues	18	5	45	67
Hardware and other | Corporate
Disaggregation of Revenue
Total revenues	0	6,153	2	6,150
Products and services transferred at a point in time
Disaggregation of Revenue
Total revenues	17,786	26,453	37,672	47,552
Products and services transferred at a point in time | Software licenses and royalties
Disaggregation of Revenue
Total revenues	14,468	15,802	30,534	32,712
Products and services transferred at a point in time | Subscriptions
Disaggregation of Revenue
Total revenues	0	0	0	0
Products and services transferred at a point in time | Software services
Disaggregation of Revenue
Total revenues	0	0	0	0
Products and services transferred at a point in time | Maintenance
Disaggregation of Revenue
Total revenues	0	0	0	0
Products and services transferred at a point in time | Appraisal services
Disaggregation of Revenue
Total revenues	0	0	0	0
Products and services transferred at a point in time | Hardware and other
Disaggregation of Revenue
Total revenues	3,318	10,651	7,138	14,840
Products and services transferred over time
Disaggregation of Revenue
Total revenues	253,305	248,671	509,960	474,638
Products and services transferred over time | Software licenses and royalties
Disaggregation of Revenue
Total revenues	2,557	4,873	5,228	9,756
Products and services transferred over time | Subscriptions
Disaggregation of Revenue
Total revenues	85,638	73,475	167,361	140,750
Products and services transferred over time | Software services
Disaggregation of Revenue
Total revenues	43,654	57,401	95,787	105,844
Products and services transferred over time | Maintenance
Disaggregation of Revenue
Total revenues	116,760	106,689	231,125	206,841
Products and services transferred over time | Appraisal services
Disaggregation of Revenue
Total revenues	4,696	6,233	10,459	11,447
Products and services transferred over time | Hardware and other
Disaggregation of Revenue
Total revenues	$ 0	$ 0	$ 0	$ 0