Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2021	Mar. 31, 2020
Disaggregation of Revenue
Total revenues	$ 294,802	$ 276,541
Intercompany
Disaggregation of Revenue
Total revenues	(5,276)	(4,019)
Intercompany \| Enterprise Software
Disaggregation of Revenue
Total revenues	5,261	4,001
Intercompany \| Appraisal and Tax
Disaggregation of Revenue
Total revenues	15	18
Operating segments \| Enterprise Software
Disaggregation of Revenue
Total revenues	269,608	250,177
Operating segments \| Appraisal and Tax
Disaggregation of Revenue
Total revenues	30,470	30,381
Corporate
Disaggregation of Revenue
Total revenues	(5,276)	(4,017)
Corporate and Elimination
Disaggregation of Revenue
Total revenues	(5,276)	(4,017)
Recurring revenues
Disaggregation of Revenue
Total revenues	221,591	196,088
Recurring revenues \| Enterprise Software
Disaggregation of Revenue
Total revenues	204,614	181,485
Recurring revenues \| Appraisal and Tax
Disaggregation of Revenue
Total revenues	16,977	14,603
Recurring revenues \| Corporate
Disaggregation of Revenue
Total revenues	0	0
Non-recurring revenues
Disaggregation of Revenue
Total revenues	73,211	80,453
Non-recurring revenues \| Enterprise Software
Disaggregation of Revenue
Total revenues	59,733	64,691
Non-recurring revenues \| Appraisal and Tax
Disaggregation of Revenue
Total revenues	13,478	15,760
Non-recurring revenues \| Corporate
Disaggregation of Revenue
Total revenues	0	2
Software licenses and royalties
Disaggregation of Revenue
Total revenues	14,933	18,737
Software licenses and royalties \| Enterprise Software
Disaggregation of Revenue
Total revenues	13,047	15,951
Software licenses and royalties \| Appraisal and Tax
Disaggregation of Revenue
Total revenues	1,886	2,786
Software licenses and royalties \| Corporate
Disaggregation of Revenue
Total revenues	0	0
Subscriptions
Disaggregation of Revenue
Total revenues	102,479	81,723
Subscriptions \| Enterprise Software
Disaggregation of Revenue
Total revenues	94,831	76,644
Subscriptions \| Appraisal and Tax
Disaggregation of Revenue
Total revenues	7,648	5,079
Subscriptions \| Corporate
Disaggregation of Revenue
Total revenues	0	0
Software services
Disaggregation of Revenue
Total revenues	47,640	52,133
Software services \| Enterprise Software
Disaggregation of Revenue
Total revenues	42,560	44,949
Software services \| Appraisal and Tax
Disaggregation of Revenue
Total revenues	5,080	7,184
Software services \| Corporate
Disaggregation of Revenue
Total revenues	0	0
Maintenance
Disaggregation of Revenue
Total revenues	119,112	114,365
Maintenance \| Enterprise Software
Disaggregation of Revenue
Total revenues	109,783	104,841
Maintenance \| Appraisal and Tax
Disaggregation of Revenue
Total revenues	9,329	9,524
Maintenance \| Corporate
Disaggregation of Revenue
Total revenues	0	0
Appraisal services
Disaggregation of Revenue
Total revenues	6,465	5,763
Appraisal services \| Enterprise Software
Disaggregation of Revenue
Total revenues	0	0
Appraisal services \| Appraisal and Tax
Disaggregation of Revenue
Total revenues	6,465	5,763
Appraisal services \| Corporate
Disaggregation of Revenue
Total revenues	0	0
Hardware and other
Disaggregation of Revenue
Total revenues	4,173	3,820
Hardware and other \| Enterprise Software
Disaggregation of Revenue
Total revenues	4,126	3,791
Hardware and other \| Appraisal and Tax
Disaggregation of Revenue
Total revenues	47	27
Hardware and other \| Corporate
Disaggregation of Revenue
Total revenues	0	2
Products and services transferred at a point in time
Disaggregation of Revenue
Total revenues	16,231	19,886
Products and services transferred at a point in time \| Software licenses and royalties
Disaggregation of Revenue
Total revenues	12,058	16,066
Products and services transferred at a point in time \| Subscriptions
Disaggregation of Revenue
Total revenues	0	0
Products and services transferred at a point in time \| Software services
Disaggregation of Revenue
Total revenues	0	0
Products and services transferred at a point in time \| Maintenance
Disaggregation of Revenue
Total revenues	0	0
Products and services transferred at a point in time \| Appraisal services
Disaggregation of Revenue
Total revenues	0	0
Products and services transferred at a point in time \| Hardware and other
Disaggregation of Revenue
Total revenues	4,173	3,820
Products and services transferred over time
Disaggregation of Revenue
Total revenues	278,571	256,655
Products and services transferred over time \| Software licenses and royalties
Disaggregation of Revenue
Total revenues	2,875	2,671
Products and services transferred over time \| Subscriptions
Disaggregation of Revenue
Total revenues	102,479	81,723
Products and services transferred over time \| Software services
Disaggregation of Revenue
Total revenues	47,640	52,133
Products and services transferred over time \| Maintenance
Disaggregation of Revenue
Total revenues	119,112	114,365
Products and services transferred over time \| Appraisal services
Disaggregation of Revenue
Total revenues	6,465	5,763
Products and services transferred over time \| Hardware and other
Disaggregation of Revenue
Total revenues	$ 0	$ 0