Acquisitions - Recognized Amounts of Identifiable Assets Acquired and Liabilities Assumed 2018 (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	May 02, 2018
Business Acquisition [Line Items]
Cash	$ 29,507	$ 28,395
Accounts receivable and other tangible assets	33,700	38,244
Accounts payable and other liabilities	(24,385)	(14,997)
Deferred revenue	(6,872)	(6,880)
Net deferred tax liabilities	(57,659)	(64,539)
Total identifiable net assets	236,977	284,018
Goodwill	593,055	844,770
Developed Software and Core Technologies
Business Acquisition [Line Items]
Finite-lived intangible assets	215,714	225,163
Customer Lists
Business Acquisition [Line Items]
Finite-lived intangible assets	27,016	61,659
Trade Names
Business Acquisition [Line Items]
Finite-lived intangible assets	$ 19,956	$ 17,230
OPTIS
Business Acquisition [Line Items]
Cash			$ 7,957
Accounts receivable and other tangible assets			15,910
Accounts payable and other liabilities			(11,941)
Deferred revenue			(2,470)
Net deferred tax liabilities			(23,438)
Total identifiable net assets			85,667
Goodwill			205,316
OPTIS | Developed Software and Core Technologies
Business Acquisition [Line Items]
Finite-lived intangible assets			47,597
OPTIS | Customer Lists
Business Acquisition [Line Items]
Finite-lived intangible assets			41,303
OPTIS | Trade Names
Business Acquisition [Line Items]
Finite-lived intangible assets			$ 10,749