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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, 2019 USD ($) shares
Business Acquisition [Line Items] |
Common Shares Issued | shares | 1,787
Common Share Value | $ 155,900,000
Cash Paid | 1,274,500,000
Accrued Liability | 16,400,000
Escrow Deposited | 72,800,000
Recorded Earnout Payable | 272,200,000
Total Recorded Purchase Price | 1,791,800,000
Maximum Potential Earnout Payable | $ 477,100,000
Inverson Holding Company - Company, LLC (IHC) [Member] |
Business Acquisition [Line Items] |
Common Shares Issued | shares | 452
Common Share Value | $ 35,900,000
Cash Paid | 31,200,000
Escrow Deposited | 4,500,000
Recorded Earnout Payable | 20,800,000
Total Recorded Purchase Price | 92,400,000
Maximum Potential Earnout Payable | 35,000,000.0
James Brown Inc. (JBI) [Member] |
Business Acquisition [Line Items] |
Cash Paid | 65,900,000
Escrow Deposited | 8,700,000
Total Recorded Purchase Price | 74,600,000
Limited SPG [Member] |
Business Acquisition [Line Items] |
Cash Paid | 326,800,000
Escrow Deposited | 4,800,000
Total Recorded Purchase Price | 331,600,000
RPA Insurance Services LLC [Member] |
Business Acquisition [Line Items] |
Cash Paid | 44,000,000.0
Escrow Deposited | 3,900,000
Recorded Earnout Payable | 16,900,000
Total Recorded Purchase Price | 64,800,000
Maximum Potential Earnout Payable | 22,000,000.0
JLT Aerospace [Member] |
Business Acquisition [Line Items] |
Cash Paid | 162,800,000
Recorded Earnout Payable | 67,900,000
Total Recorded Purchase Price | 230,700,000
Maximum Potential Earnout Payable | 75,100,000
RGA Group [Member] |
Business Acquisition [Line Items] |
Cash Paid | 42,800,000
Accrued Liability | 6,000,000.0
Escrow Deposited | 4,700,000
Recorded Earnout Payable | 8,000,000.0
Total Recorded Purchase Price | 61,500,000
Maximum Potential Earnout Payable | $ 9,300,000
LSG Insurance Partners, Inc. (LSG) [Member] |
Business Acquisition [Line Items] |
Common Shares Issued | shares | 395
Common Share Value | $ 36,200,000
Cash Paid | 127,200,000
Escrow Deposited | 6,000,000.0
Recorded Earnout Payable | 50,100,000
Total Recorded Purchase Price | 219,500,000
Maximum Potential Earnout Payable | $ 71,500,000
The EHE Group, LLC dba BonusDrive (EHE) [Member] |
Business Acquisition [Line Items] |
Common Shares Issued | shares | 458
Common Share Value | $ 42,000,000.0
Cash Paid | 41,000,000.0
Accrued Liability | 200,000
Escrow Deposited | 1,000,000.0
Recorded Earnout Payable | 27,000,000.0
Total Recorded Purchase Price | 111,200,000
Maximum Potential Earnout Payable | 77,000,000.0
Horseshoe Insurance Services Holdings, Ltd. (HIS) [Member] |
Business Acquisition [Line Items] |
Cash Paid | 43,300,000
Accrued Liability | 8,500,000
Escrow Deposited | 5,000,000.0
Recorded Earnout Payable | 7,100,000
Total Recorded Purchase Price | 63,900,000
Maximum Potential Earnout Payable | $ 10,000,000.0
40 other acquisitions [Member] |
Business Acquisition [Line Items] |
Common Shares Issued | shares | 482
Common Share Value | $ 41,800,000
Cash Paid | 389,500,000
Accrued Liability | 1,700,000
Escrow Deposited | 34,200,000
Recorded Earnout Payable | 74,400,000
Total Recorded Purchase Price | 541,600,000
Maximum Potential Earnout Payable | $ 177,200,000

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