Goodwill and Intangible Assets - Intangible Assets (Detail) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Intangible Assets [Line Items]
Amortized intangible assets, gross carrying amount	$ 1,089,690	$ 1,058,951
Amortized intangible assets, accumulated amortization	(615,262)	(582,597)
Indefinite-lived intangible assets (excluding goodwill)	357
Trade Names
Intangible Assets [Line Items]
Indefinite-lived intangible assets (excluding goodwill)	357	357
Developed Software and Core Technologies
Intangible Assets [Line Items]
Amortized intangible assets, gross carrying amount	670,429	635,063
Amortized intangible assets, accumulated amortization	(359,230)	(332,622)
Customer Lists
Intangible Assets [Line Items]
Amortized intangible assets, gross carrying amount	262,744	269,629
Amortized intangible assets, accumulated amortization	(135,148)	(132,596)
Trade Names
Intangible Assets [Line Items]
Amortized intangible assets, gross carrying amount	156,517	154,259
Amortized intangible assets, accumulated amortization	$ (120,884)	$ (117,379)