Commitments, Contingencies and Off-Balance Sheet Arrangements - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2023 USD ($) ft² LetterOfCredit Employee	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Number of square feet | ft²	360,000
Number of employees will accommodate at new facility | Employee	2,000
Total rent expense	$ 183,500,000	$ 176,600,000	$ 153,400,000
Aggregate amount of maximum earnout obligations related to acquisitions	2,009,800,000	1,946,200,000
Aggregate amount of maximum earnout obligations related to acquisitions, recorded in consolidated balance sheet	1,294,200,000	1,077,300,000
Aggregate amount of earnout obligation expected settlement in cash or stock at option	564,800,000	734,000,000
Aggregate amount of earnout obligation expected settlement in cash	729,400,000	$ 343,300,000
Debt	23,600,000
Liabilities recorded on self-insurance	13,700,000
Income tax credits and adjustments	$ 108,000,000.0
Collateral [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Number of letters of credit issued | LetterOfCredit	1
Security Deposit [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Number of letters of credit issued | LetterOfCredit	1
Self-Insurance Deductibles [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Number of letters of credit issued | LetterOfCredit	2
Rent-A-Captive Facility [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Number of letters of credit issued | LetterOfCredit	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
Insurance claim arise during ordinary course of business	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] | Collateral [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Debt	500,000
Letter of Credit [Member] | Security Deposit [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Debt	900,000
Letter of Credit [Member] | Self-Insurance Deductibles [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Debt	9,300,000
Liabilities recorded on self-insurance	13,700,000
Letter of Credit [Member] | Rent-A-Captive Facility [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Debt	10,500,000
Minimum [Member] | Errors And Omissions [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Actuarial range value	6,700,000
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
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
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
Minimum [Member] | Unconsolidated Investments in Enterprises [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Ownership interest	1.00%
Maximum [Member] | Errors And Omissions [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Actuarial range value	$ 6,900,000
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
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
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
Maximum [Member] | Unconsolidated Investments in Enterprises [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Ownership interest	50.00%
Tax Increment Financing [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Property tax credits receivable period	15 years
Economic development for growing economy tax credit	$ 51,300,000
Tax Increment Financing [Member] | Minimum [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Property tax credit expect to receive	50,000,000
Tax Increment Financing [Member] | Maximum [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Property tax credit expect to receive	$ 80,000,000