SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Additional Information (Details)	12 Months Ended
	Dec. 31, 2021 USD ($) subsidiary	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Mar. 09, 2021 USD ($)	Dec. 31, 2018 USD ($)
Accounting Policies
Total revenues	$ 1,592,287,000	$ 1,116,663,000	$ 1,086,427,000
Recurring revenue percentage of total revenue (percent)	79.00%
Cash and investments	$ 407,800,000
Number of wholly-owned subsidiaries | subsidiary	60
Accounts receivable, net	$ 535,000,000	403,700,000
Accounts receivable, allowance for losses	$ 12,086,000	9,255,000	5,738,000
Sales commission, renewal period	1 year
Research and development expense	$ 93,481,000	88,363,000	81,342,000
Impairments of intangible assets	0	0	0
Impairments of long-lived assets	0	0	0
Capitalized post acquisition software development costs	21,700,000	5,800,000
Amortization of software development costs	2,300,000	1,200,000	296,000
Cash and cash equivalents	309,171,000	603,623,000	232,682,000		$ 134,279,000
Goodwill	$ 2,359,674,000	838,428,000	840,117,000
Software and Software Development Costs
Accounting Policies
Remaining estimated economic life	5 years
Case Management, Business Process Management, Data And Insight
Accounting Policies
Percentage of total goodwill	68.00%
Goodwill	$ 1,600,000,000
Minimum
Accounting Policies
Typical contract term (in years)	3 years
Contract term (in years)	1 year
Progress billing retention percentage	5.00%
Payment term	30 days
Sales commissions amortization period (in years)	3 years
Maximum
Accounting Policies
Typical contract term (in years)	5 years
Contract term (in years)	10 years
Progress billing retention percentage	15.00%
Payment term	90 days
Sales commissions amortization period (in years)	7 years
Stock Option Plan
Accounting Policies
Share based compensation contractual term (in years)	10 years
Stock Option Plan | Minimum
Accounting Policies
Share based compensation vesting period (in years)	3 years
Stock Option Plan | Maximum
Accounting Policies
Share based compensation vesting period (in years)	6 years
Unbilled Revenues
Accounting Policies
Accounts receivable, net	$ 140,300,000	140,800,000
Unbilled Revenues | Retention Receivable
Accounting Policies
Accounts receivable, net	$ 7,700,000	13,100,000
SaaS arrangements services | Minimum
Accounting Policies
Typical contract term (in years)	3 years
Contract term (in years)	1 year
SaaS arrangements services | Maximum
Accounting Policies
Typical contract term (in years)	5 years
Contract term (in years)	10 years
Appraisal services
Accounting Policies
Total revenues	$ 27,788,000	$ 21,127,000	$ 23,479,000
Appraisal services | Minimum
Accounting Policies
Contract term (in years)	1 year
Appraisal services | Maximum
Accounting Policies
Contract term (in years)	3 years
Software Licenses Royalties and Software Services | Tour Health
Accounting Policies
Total revenues	$ 75,000,000
Convertible Senior Notes Due 2026 | Senior Notes
Accounting Policies
Debt instrument face amount	600,000,000			$ 600,000,000
Revolving Credit Facility | 2021 Credit Agreement
Accounting Policies
Debt instrument face amount	755,000,000
Revolving Credit Facility | Senior Unsecured Revolving Credit Facility
Accounting Policies
Line of credit facility, unused borrowing capacity	$ 500,000,000