Supplemental Disclosures of Cash Flow Information and Non-Cash Financing and Investing Activities - Summary of Significant Non-Cash Investing and Financing Activities (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Significant non-cash investing and financing activities
Other payables issued for agency acquisitions and purchased customer accounts	$ 5.6	$ 15.1	$ 9.1
Estimated acquisition earn-out payables and related charges	73.3	75.7	$ 131.4
Assumed acquisition earn-out payables	34.8
Contingent payable issued for agency acquisition		24.1
Common stock issued for agency acquisition	14.7	9.9
Notes payable assumed for agency acquisition	$ 1.8	$ 1.4

The amount of payables that an Entity assumes in acquiring a business or in consideration for an asset received in a noncash (or part noncash) acquisition. Noncash is defined as transactions during a period that affect recognized assets or liabilities but that do not result in cash receipts or cash payments in the period. "Part noncash" refers to that portion of the transaction not resulting in cash receipts or cash payments in the period.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 50
-Paragraph 4
-URI https://asc.fasb.org/extlink&oid=126999549&loc=d3e4313-108586

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 50
-Paragraph 5
-URI https://asc.fasb.org/extlink&oid=126999549&loc=d3e4332-108586

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 50
-Paragraph 3
-URI https://asc.fasb.org/extlink&oid=126999549&loc=d3e4304-108586

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