Lines of Credit, Long-Term Debt, Commitments and Contingencies (Details) $ in Millions							3 Months Ended	6 Months Ended
	Sep. 30, 2021 USD ($)	Jul. 21, 2021	Jun. 28, 2018 plaintiff	May 15, 2018 USD ($)	Apr. 27, 2018 USD ($) employee	Mar. 20, 2018 USD ($) subsidiary	Jul. 03, 2021 USD ($)	Dec. 31, 2018 plaintiff	Oct. 02, 2021 USD ($)	May 29, 2021 USD ($)	Apr. 03, 2021 USD ($)	Dec. 31, 2020 USD ($)
Lines of Credit, Long-Term Debt, Commitments and Contingencies
Lines of credit outstanding									$ 467.0			$ 222.0
Other long-term debt									39.0			30.0
Total debt at face value									718.0			763.0
Current maturities of long-term debt and unamortized discount									(9.0)			(56.0)
Long-term debt, less current maturities									709.0			707.0
Current maturities of long-term debt									8.0			55.0
Contingencies
Assets									$ 7,257.0			$ 6,399.0
Pork Product Purchasers | Pending Litigation
Contingencies
Number of plaintiffs | plaintiff			12					3
Odette Blanco De Fernandez | Pending Litigation
Contingencies
Term of concession to develop port facilities		70 years
HSBC | Pending Litigation
Contingencies
Damages sought	$ 10.0
HSBC | Pending Litigation | Minimum
Contingencies
Interest and other relief sought	$ 3.2
Cereoil
Contingencies
Percentage of ownership									45.00%
Cereoil | Cereoil Bankruptcy Trustee - Case One | Pending Litigation
Contingencies
Damages sought						$ 22.0
Number of subsidiaries | subsidiary						2
Cereoil | Cereoil Bankruptcy Trustee - Case Two | Pending Litigation
Contingencies
Damages sought					$ 23.0
Number of individuals employed by Seaboard serving as directors | employee					2
Total liabilities					$ 53.0
Assets					$ 30.0
Nolston
Contingencies
Percentage of ownership									45.00%
Nolston | Nolston Bankruptcy Trustee | Pending Litigation
Contingencies
Damages sought				$ 14.0
Total liabilities				29.0
Assets				$ 15.0
Committed and uncommitted bank lines
Lines of Credit, Long-Term Debt, Commitments and Contingencies
Weighted average interest rate (as a percent)									3.00%			3.89%
Uncommitted bank lines
Lines of Credit, Long-Term Debt, Commitments and Contingencies
Lines of credit outstanding									$ 366.0			$ 222.0
Uncommitted bank lines | Denominated in foreign currencies
Lines of Credit, Long-Term Debt, Commitments and Contingencies
Lines of credit outstanding									216.0			142.0
Uncommitted bank lines | South African Rand
Lines of Credit, Long-Term Debt, Commitments and Contingencies
Lines of credit outstanding									198.0			106.0
Uncommitted bank lines | Denominated in Canadian dollars
Lines of Credit, Long-Term Debt, Commitments and Contingencies
Lines of credit outstanding												25.0
Committed bank line
Lines of Credit, Long-Term Debt, Commitments and Contingencies
Lines of credit outstanding												0.0
Committed credit line #1
Lines of Credit, Long-Term Debt, Commitments and Contingencies
Lines of credit outstanding									101.0
Maximum capacity							$ 250.0				$ 100.0
Committed credit line #2
Lines of Credit, Long-Term Debt, Commitments and Contingencies
Maximum capacity										$ 250.0
Term loan due 2028
Lines of Credit, Long-Term Debt, Commitments and Contingencies
Debt at face value									$ 679.0			$ 684.0
Effective interest rate (as a percent)									1.71%			1.77%
Foreign subsidiary obligations
Lines of Credit, Long-Term Debt, Commitments and Contingencies
Debt at face value												$ 49.0
Foreign subsidiary obligations | Denominated in Euros
Lines of Credit, Long-Term Debt, Commitments and Contingencies
Total debt at face value												$ 46.0
Equipment loan
Lines of Credit, Long-Term Debt, Commitments and Contingencies
Interest rate (as a percent)							5.60%
Long-term debt assumed							$ 9.0