Commitments, Contingencies and Off-Balance Sheet Arrangements - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2021 USD ($) ft² Employee LetterOfCredit	Dec. 31, 2020 USD ($)	Dec. 31, 2019 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	$ 153,400,000	$ 154,000,000.0	$ 148,100,000
Aggregate amount of maximum earnout obligations related to acquisitions	1,873,900,000	1,128,100,000
Aggregate amount of maximum earnout obligations related to acquisitions, recorded in consolidated balance sheet	988,500,000	592,200,000
Aggregate amount of earnout obligation expected settlement in cash or stock at option	670,300,000	493,700,000
Aggregate amount of earnout obligation expected settlement in cash	$ 318,200,000	$ 98,500,000
Ownership interest	50.00%
Debt	$ 22,600,000
Liabilities recorded on self-insurance	18,300,000
Income tax credits and adjustments	$ 108,000,000.0
Security Deposit [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Number of letters of credit issued | LetterOfCredit	2
Collateral [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	8
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	20,000,000.0
Errors And Omissions [Member] | Up to $27.0 Million [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Insurance claims, amount retained	10,000,000.0
Letter of Credit [Member] | Security Deposit [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Debt	600,000
Letter of Credit [Member] | Collateral [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	9,400,000
Liabilities recorded on self-insurance	18,300,000
Letter of Credit [Member] | Rent-A-Captive Facility [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Debt	6,100,000
Minimum [Member] | Errors And Omissions [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Actuarial range value	3,700,000
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]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Ownership interest	50.00%
Maximum [Member] | Errors And Omissions [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Actuarial range value	$ 5,800,000
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	$ 365,000,000.0
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	$ 32,600,000
Tax Increment Financing [Member] | Minimum [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Property tax credit expect to receive	60,000,000.0
Tax Increment Financing [Member] | Maximum [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Property tax credit expect to receive	$ 90,000,000.0