Commitments, Contingencies and Off-Balance Sheet Arrangements - Outstanding Letters of Credit, Financial Guarantees and Funding Commitments (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2023 USD ($)
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Maximum Exposure	$ 23.6
Liability Recorded	$ 13.7
Funding Commitment to an Equity Investment - to be Funded in 2024 [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Collateral	None
Compensation to Us	None
Investment, Type [Extensible Enumeration]	Venture Capital Funds And Other [Member]
Credit Support Under Letters of Credit for Deductibles Due by Us on Our Own Insurance Coverage's Expires After 2028 [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Collateral	None
Compensation to Us	None
Maximum Exposure	$ 9.3
Liability Recorded	$ 13.7
Credit Enhancement Under Letters of Credit for Our Captive Insurance Operations to Meet Minimum Statutory Capital Requirement's Expires After 2024 and 2028 [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Collateral	None
Compensation to Us	Reimbursement of LOC fees
Maximum Exposure	$ 10.5
Collateral Related To Claim Funds Held in a Fiduciary Capacity by a Recent Acquisition Expires 2028 [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Collateral	None
Compensation to Us	None
Maximum Exposure	$ 0.9
Credit Support Under Letters of Credit in Lieu of Security Deposit for One Lease from Acquisitions Expires 2028 [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Collateral	None
Compensation to Us	None
Maximum Exposure	$ 0.5
Financial Guarantees of Loans to Five Canadian Based Employees Trigger [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Collateral	(1)
Compensation to Us	None
Maximum Exposure	$ 0.6
Financial Guarantee of External Loan to Subsidiary in Chile Expires when Loan Balance is Reduced to Zero through July 2024 - Principal and Interest are Paid Quarterly [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Collateral	None
Compensation to Us	None
Maximum Exposure	$ 1.8