Goodwill and Other Intangible Assets, Net - Components of Goodwill and Other Intangible Assets, Net (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Finite-Lived Intangible Assets [Line Items]
Goodwill	$ 740,743	$ 683,083	$ 588,213
Intangibles :
Total intangibles	260,876	218,328
Total goodwill and other intangibles assets	1,001,619	901,411
Accumulated amortization:
Total accumulated amortization	(160,836)	(144,661)
Goodwill and other intangible assets, net	840,783	756,750
Client lists
Intangibles :
Total intangibles	249,422	207,084
Accumulated amortization:
Total accumulated amortization	(152,326)	(137,284)
Other intangibles
Intangibles :
Total intangibles	11,454	11,244
Accumulated amortization:
Total accumulated amortization	$ (8,510)	$ (7,377)