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Commitments, Contingencies and Off-Balance Sheet Arrangements - Additional Information (Detail) | 3 Months Ended | 9 Months Ended | 261 Months Ended
--- | --- | --- | ---
Sep. 30, 2023 USD ($) ft² LetterOfCredit Entity | Sep. 30, 2022 Entity | Sep. 30, 2023 USD ($) ft² LetterOfCredit Entity | Sep. 30, 2022 Entity | Sep. 30, 2023 USD ($) ft² LetterOfCredit Entity
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items] |  |  |  |  |
Number of square feet | ft² | 360,000 |  | 360,000 |  | 360,000
Number of companies acquired | Entity | 20 | 27 | 59 | 70 | 687
Aggregate amount of maximum earnout obligations related to acquisitions |  |  | $ 1,915,700,000 |  |
Aggregate amount of maximum earnout obligations related to acquisitions, recorded in consolidated balance sheet |  |  | 899,000,000 |  |
Aggregate amount of earnout obligation expected settlement in cash or stock at option | $ 486,600,000 |  | 486,600,000 |  | $ 486,600,000
Aggregate amount of earnout obligation expected settlement in cash | $ 412,400,000 |  | 412,400,000 |  | $ 412,400,000
Income tax credits and adjustments |  |  | $ 108,000,000 |  |
Security Deposit [Member] |  |  |  |  |
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items] |  |  |  |  |
Number of letters of credit issued | LetterOfCredit | 2 |  | 2 |  | 2
Self-Insurance Deductibles [Member] |  |  |  |  |
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items] |  |  |  |  |
Number of letters of credit issued | LetterOfCredit | 2 |  | 2 |  | 2
Rent-A-Captive Facility [Member] |  |  |  |  |
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items] |  |  |  |  |
Number of letters of credit issued | LetterOfCredit | 9 |  | 9 |  | 9
Errors And Omissions [Member] | Up to $4.5 Million [Member] |  |  |  |  |
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items] |  |  |  |  |
Insurance claims, amount retained |  |  | $ 2,000,000.0 |  |
Errors And Omissions [Member] | Up to $10 Million [Member] |  |  |  |  |
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items] |  |  |  |  |
Insurance claims, amount retained |  |  | 15,000,000.0 |  |
Errors And Omissions [Member] | Up to $20.0 Million [Member] |  |  |  |  |
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items] |  |  |  |  |
Insurance claims, amount retained |  |  | 10,000,000.0 |  |
Errors And Omissions [Member] | Up to $27.0 Million [Member] |  |  |  |  |
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items] |  |  |  |  |
Insurance claims, amount retained |  |  | 20,000,000.0 |  |
Letter of Credit [Member] | Security Deposit [Member] |  |  |  |  |
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items] |  |  |  |  |
Debt | $ 500,000 |  | 500,000 |  | $ 500,000
Letter of Credit [Member] | Self-Insurance Deductibles [Member] |  |  |  |  |
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items] |  |  |  |  |
Debt | 9,300,000 |  | 9,300,000 |  | 9,300,000
Liabilities recorded on self-insurance | 13,300,000 |  | 13,300,000 |  | 13,300,000
Letter of Credit [Member] | Rent-A-Captive Facility [Member] |  |  |  |  |
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items] |  |  |  |  |
Debt | 8,300,000 |  | 8,300,000 |  | 8,300,000
Minimum [Member] | Errors And Omissions [Member] |  |  |  |  |
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items] |  |  |  |  |
Actuarial range value | 5,800,000 |  | 5,800,000 |  | 5,800,000
Minimum [Member] | Errors And Omissions [Member] | Up to $4.5 Million [Member] |  |  |  |  |
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items] |  |  |  |  |
Insurance claim arise during ordinary course of business | 15,000,000.0 |  | 15,000,000.0 |  | 15,000,000.0
Minimum [Member] | Errors And Omissions [Member] | Up to $20.0 Million [Member] |  |  |  |  |
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items] |  |  |  |  |
Insurance claim arise during ordinary course of business | 100,000,000.0 |  | 100,000,000.0 |  | 100,000,000.0
Minimum [Member] | Errors And Omissions [Member] | Up to $27.0 Million [Member] |  |  |  |  |
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items] |  |  |  |  |
Insurance claim arise during ordinary course of business | 225,000,000.0 |  | 225,000,000.0 |  | 225,000,000.0
Maximum [Member] | Errors And Omissions [Member] |  |  |  |  |
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items] |  |  |  |  |
Actuarial range value | 8,100,000 |  | 8,100,000 |  | 8,100,000
Maximum [Member] | Errors And Omissions [Member] | Up to $4.5 Million [Member] |  |  |  |  |
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items] |  |  |  |  |
Insurance claim arise during ordinary course of business | 100,000,000.0 |  | 100,000,000.0 |  | 100,000,000.0
Maximum [Member] | Errors And Omissions [Member] | Up to $20.0 Million [Member] |  |  |  |  |
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items] |  |  |  |  |
Insurance claim arise during ordinary course of business | 225,000,000.0 |  | 225,000,000.0 |  | 225,000,000.0
Maximum [Member] | Errors And Omissions [Member] | Up to $27.0 Million [Member] |  |  |  |  |
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items] |  |  |  |  |
Insurance claim arise during ordinary course of business | $ 400,000,000.0 |  | $ 400,000,000.0 |  | $ 400,000,000.0
Unconsolidated Investments in Enterprises [Member] | Minimum [Member] |  |  |  |  |
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items] |  |  |  |  |
Ownership interest | 1.00% |  | 1.00% |  | 1.00%
Unconsolidated Investments in Enterprises [Member] | Maximum [Member] |  |  |  |  |
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items] |  |  |  |  |
Ownership interest | 50.00% |  | 50.00% |  | 50.00%

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