Goodwill and Intangible Assets - Schedule of intangible assets (Detail) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2022	Dec. 31, 2021
Finite-lived Intangible Assets [Roll Forward]
Gross Carrying Value	$ 2,646,360	$ 2,637,733
Accumulated Amortization	1,345,403	1,250,219
Net Carrying Value	1,300,957	1,387,514
Indefinite-lived Intangible Assets [Roll Forward]
Indefinite-lived Intangible Assets (Excluding Goodwill)	900,000	900,000
Indefinite-Lived Trade Names	900,000	900,000
Intangible Assets, Gross (Excluding Goodwill)	3,546,360	3,537,733
Other Intangible Assets Accumulated Amortization	1,345,403	1,250,219
Intangible Assets, Net (Including Goodwill)	$ 2,200,957	$ 2,287,514
Client relationships [Member]
Finite-lived Intangible Assets [Roll Forward]
Weighted Average Useful Life	14 years	14 years
Gross Carrying Value	$ 2,491,082	$ 2,480,167
Accumulated Amortization	1,247,588	1,158,732
Net Carrying Value	$ 1,243,494	$ 1,321,435
Trade names [Member]
Finite-lived Intangible Assets [Roll Forward]
Weighted Average Useful Life	8 years	8 years
Gross Carrying Value	$ 135,918	$ 138,206
Accumulated Amortization	82,836	78,355
Net Carrying Value	$ 53,082	$ 59,851
Developed technology [Member]
Finite-lived Intangible Assets [Roll Forward]
Weighted Average Useful Life	5 years	5 years
Gross Carrying Value	$ 13,260	$ 13,260
Accumulated Amortization	9,443	8,206
Net Carrying Value	$ 3,817	$ 5,054
Covenant not to compete [Member]
Finite-lived Intangible Assets [Roll Forward]
Weighted Average Useful Life	5 years	5 years
Gross Carrying Value	$ 6,100	$ 6,100
Accumulated Amortization	5,536	4,926
Net Carrying Value	$ 564	$ 1,174