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Business Combinations - Acquisition Method for Recording Business Combinations (Detail) shares in Thousands | 12 Months Ended
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Dec. 31, 2021 USD ($) shares
Atlas General Holdings LLC [Member] |
Business Acquisition [Line Items] |
Cash Paid | $ 95,200,000
Escrow Deposited | 5,400,000
Recorded Earnout Payable | 8,700,000
Total Recorded Purchase Price | 109,300,000
Maximum Potential Earnout Payable | 35,000,000.0
Bollington Wilson Group [Member] |
Business Acquisition [Line Items] |
Cash Paid | 328,000,000.0
Escrow Deposited | 1,400,000
Total Recorded Purchase Price | 329,400,000
LDJ American Online Benefits Group, LLC [Member] |
Business Acquisition [Line Items] |
Cash Paid | 38,200,000
Escrow Deposited | 7,100,000
Recorded Earnout Payable | 14,800,000
Total Recorded Purchase Price | 60,100,000
Maximum Potential Earnout Payable | 20,000,000.0
Edelweiss Gallagher Insurance Brokers Limited [Member] |
Business Acquisition [Line Items] |
Cash Paid | 35,700,000
Accrued Liability | 5,300,000
Recorded Earnout Payable | 8,500,000
Total Recorded Purchase Price | 49,500,000
Maximum Potential Earnout Payable | 9,900,000
Manchester Underwriting Agencies Limited [Member] |
Business Acquisition [Line Items] |
Cash Paid | 33,000,000.0
Accrued Liability | 3,900,000
Escrow Deposited | 1,400,000
Recorded Earnout Payable | 16,500,000
Total Recorded Purchase Price | 54,800,000
Maximum Potential Earnout Payable | 20,600,000
Willis Reinsurance Operations [Member] |
Business Acquisition [Line Items] |
Cash Paid | 3,278,900,000
Recorded Earnout Payable | 300,000,000.0
Total Recorded Purchase Price | 3,578,900,000
Maximum Potential Earnout Payable | $ 750,000,000.0
Thirty-Two Other Acquisitions [Member] |
Business Acquisition [Line Items] |
Common Shares Issued | shares | 1,008
Common Share Value | $ 149,900,000
Cash Paid | 224,200,000
Accrued Liability | 19,000,000.0
Escrow Deposited | 30,100,000
Recorded Earnout Payable | 66,300,000
Total Recorded Purchase Price | 489,500,000
Maximum Potential Earnout Payable | $ 133,900,000
2021 Acquisitions [Member] |
Business Acquisition [Line Items] |
Common Shares Issued | shares | 1,008
Common Share Value | $ 149,900,000
Cash Paid | 4,033,200,000
Accrued Liability | 28,200,000
Escrow Deposited | 45,400,000
Recorded Earnout Payable | 414,800,000
Total Recorded Purchase Price | 4,671,500,000
Maximum Potential Earnout Payable | $ 969,400,000

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- Definition Number of shares of equity interests issued or issuable to acquire entity. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 30 -Section 50 -Paragraph 1 -Subparagraph (b)(4) -URI http://asc.fasb.org/extlink&oid=120321790&loc=d3e6927-128479 + Details
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- Definition Amount of equity interests of the acquirer, including instruments or interests issued or issuable in consideration for the business combination. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 30 -Section 30 -Paragraph 8 -URI http://asc.fasb.org/extlink&oid=116859721&loc=d3e6613-128477 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 30 -Section 30 -Paragraph 7 -URI http://asc.fasb.org/extlink&oid=116859721&loc=d3e6578-128477 + Details
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- Definition The designation of funds furnished by a borrower to a lender to assure future payments of the borrower's real estate taxes and insurance obligations with respect to a mortgaged property. Escrow deposits may be made for a variety of other purposes such as earnest money and contingent payments. This element excludes replacement reserves which are an escrow separately provided for within the US GAAP taxonomy. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03.10) -URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 954 -SubTopic 440 -Section 50 -Paragraph 1 -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=6491277&loc=d3e6429-115629 + Details
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