Summary of Significant Accounting Policies - Insurance Coverage (Details)	12 Months Ended
	Dec. 31, 2024 USD ($) item policy	Dec. 31, 2023 USD ($)
Insurance Coverage
Accrued insurance claims liability	$ 4,300,000	$ 7,500,000
Marine
Insurance Coverage
Levels of insurance coverage maintained by the Company | item	5
Amount in excess of primary insurance coverage	$ 300,000,000
Marine | Other liability policies
Insurance Coverage
Primary limit of insurance coverage	1,000,000
Marine | Maritime Employer's Liability
Insurance Coverage
Primary limit of insurance coverage	10,000,000
Marine | Watercraft Pollution Policy
Insurance Coverage
Primary limit of insurance coverage	$ 5,000,000
Concrete
Insurance Coverage
Levels of insurance coverage maintained by the Company | item	5
Amount in excess of primary insurance coverage	$ 300,000,000
Number of employee health care insurance policies | policy	2
Concrete | Other liability policies
Insurance Coverage
Primary limit of insurance coverage	$ 1,000,000