Business Combinations - Aggregated Consideration And Preliminary Purchase Price Allocation (Details) - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Business Acquisition [Line Items]
Goodwill	$ 740,743	$ 683,083	$ 588,213
Series of Individually Immaterial Business Acquisitions
Business Acquisition [Line Items]
Common stock issued (in shares)	207	339
Common stock value	$ 6,940	$ 8,698
Cash paid	66,651	73,372
Other payable	0	59
Recorded contingent consideration	39,665	38,901
Total recorded purchase price	113,256	121,030
Accounts receivable acquired, net	9,838	5,381
Fixed assets acquired	1,473	0
Identifiable intangible assets acquired	42,422	20,703
Operating lease right-of-use asset acquired, net	19,153	2,746
Other assets acquired, net	848	967
Operating lease liability acquired - current	(3,020)	(793)
Other current liabilities acquired	(1,771)	(3,460)
Operating lease liability acquired - noncurrent	(16,133)	(1,953)
Goodwill	60,446	97,439
Total net assets acquired	113,256	121,030
Maximum potential contingent consideration	$ 41,720	$ 43,052