Fair Value Measurement - Narrative (Details)	3 Months Ended	12 Months Ended			36 Months Ended
	Sep. 30, 2023 USD ($)	Dec. 31, 2024 USD ($) subsidiary	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2021 USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Goodwill impairment	$ 44,100,000	$ 0	$ 44,110,000	$ 0
Number of insurance subsidiaries | subsidiary		2
Deferred compensation plan assets		$ 34,100,000	32,300,000		$ 32,300,000
Deferred compensation liabilities		33,793,000	32,043,000		32,043,000
Fair Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Deferred compensation liabilities		33,800,000	32,000,000.0		32,000,000.0
Workers' Compensation Insurance
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Goodwill, fair value	44,100,000
Goodwill impairment	$ 44,100,000		44,110,000
Fair Value, Nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value, net asset (liability)		0	$ 0		$ 0
NORCAL Group
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration period					3 years
Contingent consideration, maximum estimate		$ 84,000,000				$ 84,000,000
Corporate debt, limited observable inputs | BBB Plus
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Credit quality percentage		100.00%	98.00%		98.00%
Other asset-backed securities | Rating A A
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Credit quality percentage			79.00%		79.00%
Other asset-backed securities | Nationally Recognized Statistical Rating Organization N R S R O Rating A Minus
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Credit quality percentage		81.00%