DISAGGREGATION OF REVENUE (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Disaggregation of Revenue
Total revenues	$ 1,592,287	$ 1,116,663	$ 1,086,427
Intercompany
Disaggregation of Revenue
Total revenues	(22,988)	(19,131)	(15,496)
Corporate
Disaggregation of Revenue
Total revenues	(19,961)	(19,120)	(9,240)
Corporate and Elimination
Disaggregation of Revenue
Total revenues	(19,961)	(19,120)	(9,240)
Enterprise Software | Intercompany
Disaggregation of Revenue
Total revenues	22,921	19,061	15,290
Enterprise Software | Operating segments
Disaggregation of Revenue
Total revenues	1,122,073	1,020,959	975,319
Appraisal and Tax | Intercompany
Disaggregation of Revenue
Total revenues	67	70	206
Appraisal and Tax | Operating segments
Disaggregation of Revenue
Total revenues	121,258	114,824	120,348
NIC | Intercompany
Disaggregation of Revenue
Total revenues	0	0	0
NIC | Operating segments
Disaggregation of Revenue
Total revenues	368,917	0	0
Recurring revenues
Disaggregation of Revenue
Total revenues	1,258,721	818,160	726,670
Recurring revenues | Corporate
Disaggregation of Revenue
Total revenues	0	0	0
Recurring revenues | Enterprise Software
Disaggregation of Revenue
Total revenues	845,219	755,508	672,804
Recurring revenues | Appraisal and Tax
Disaggregation of Revenue
Total revenues	68,250	62,652	53,866
Recurring revenues | NIC
Disaggregation of Revenue
Total revenues	345,252	0	0
Non-recurring revenues
Disaggregation of Revenue
Total revenues	333,566	298,503	359,757
Non-recurring revenues | Corporate
Disaggregation of Revenue
Total revenues	3,027	11	6,256
Non-recurring revenues | Enterprise Software
Disaggregation of Revenue
Total revenues	253,933	246,390	287,225
Non-recurring revenues | Appraisal and Tax
Disaggregation of Revenue
Total revenues	52,941	52,102	66,276
Non-recurring revenues | NIC
Disaggregation of Revenue
Total revenues	23,665	0	0
Products and services transferred at a point in time
Disaggregation of Revenue
Total revenues	84,781	79,831	107,912
Products and services transferred over time
Disaggregation of Revenue
Total revenues	1,507,506	1,036,832	978,515
Software licenses and royalties
Disaggregation of Revenue
Total revenues	74,452	73,164	100,205
Software licenses and royalties | Corporate
Disaggregation of Revenue
Total revenues	0	0	0
Software licenses and royalties | Enterprise Software
Disaggregation of Revenue
Total revenues	68,101	64,200	90,808
Software licenses and royalties | Appraisal and Tax
Disaggregation of Revenue
Total revenues	6,351	8,964	9,397
Software licenses and royalties | NIC
Disaggregation of Revenue
Total revenues	0	0	0
Software licenses and royalties | Products and services transferred at a point in time
Disaggregation of Revenue
Total revenues	62,847	62,029	84,900
Software licenses and royalties | Products and services transferred over time
Disaggregation of Revenue
Total revenues	11,605	11,135	15,305
Subscriptions
Disaggregation of Revenue
Total revenues	784,435	350,648	296,352
Subscriptions | Corporate
Disaggregation of Revenue
Total revenues	0	0	0
Subscriptions | Enterprise Software
Disaggregation of Revenue
Total revenues	406,494	326,284	279,282
Subscriptions | Appraisal and Tax
Disaggregation of Revenue
Total revenues	33,249	24,364	17,070
Subscriptions | NIC
Disaggregation of Revenue
Total revenues	344,692	0	0
Subscriptions | Products and services transferred at a point in time
Disaggregation of Revenue
Total revenues	0	0	0
Subscriptions | Products and services transferred over time
Disaggregation of Revenue
Total revenues	784,435	350,648	296,352
Software services
Disaggregation of Revenue
Total revenues	209,391	186,409	213,061
Software services | Corporate
Disaggregation of Revenue
Total revenues	0	0	0
Software services | Enterprise Software
Disaggregation of Revenue
Total revenues	167,065	164,520	179,865
Software services | Appraisal and Tax
Disaggregation of Revenue
Total revenues	18,661	21,889	33,196
Software services | NIC
Disaggregation of Revenue
Total revenues	23,665	0	0
Software services | Products and services transferred at a point in time
Disaggregation of Revenue
Total revenues	0	0	0
Software services | Products and services transferred over time
Disaggregation of Revenue
Total revenues	209,391	186,409	213,061
Maintenance
Disaggregation of Revenue
Total revenues	474,287	467,513	430,318
Maintenance | Corporate
Disaggregation of Revenue
Total revenues	0	0	0
Maintenance | Enterprise Software
Disaggregation of Revenue
Total revenues	438,726	429,224	393,521
Maintenance | Appraisal and Tax
Disaggregation of Revenue
Total revenues	35,001	38,289	36,797
Maintenance | NIC
Disaggregation of Revenue
Total revenues	560	0	0
Maintenance | Products and services transferred at a point in time
Disaggregation of Revenue
Total revenues	0	0	0
Maintenance | Products and services transferred over time
Disaggregation of Revenue
Total revenues	474,287	467,513	430,318
Appraisal services
Disaggregation of Revenue
Total revenues	27,788	21,127	23,479
Appraisal services | Corporate
Disaggregation of Revenue
Total revenues	0	0	0
Appraisal services | Enterprise Software
Disaggregation of Revenue
Total revenues	0	0	0
Appraisal services | Appraisal and Tax
Disaggregation of Revenue
Total revenues	27,788	21,127	23,479
Appraisal services | NIC
Disaggregation of Revenue
Total revenues	0	0	0
Appraisal services | Products and services transferred at a point in time
Disaggregation of Revenue
Total revenues	0	0	0
Appraisal services | Products and services transferred over time
Disaggregation of Revenue
Total revenues	27,788	21,127	23,479
Hardware and other
Disaggregation of Revenue
Total revenues	21,934	17,802	23,012
Hardware and other | Products and services transferred at a point in time
Disaggregation of Revenue
Total revenues	21,934	17,802	23,012
Hardware and other | Products and services transferred over time
Disaggregation of Revenue
Total revenues	$ 0	$ 0	$ 0