Derivatives and Fair Value of Financial Instruments-Derivatives (Details) lb in Millions, gal in Millions, bu in Millions, $ in Millions	3 Months Ended	12 Months Ended
Mar. 30, 2019 USD ($) lb gal bu	Dec. 31, 2018 USD ($) lb gal bu
Equity future contracts
Derivative commodity instruments
Notional amounts \| $	$ 2	$ 97
Net commodity purchase contracts \| Grain
Derivative commodity instruments
Nonmonetary notional amount \| bu	37	33
Net commodity purchase contracts \| Soybean oil
Derivative commodity instruments
Nonmonetary notional amount		8
Net commodity sale contracts \| Hogs
Derivative commodity instruments
Nonmonetary notional amount	343	26
Net commodity sale contracts \| Soybean oil
Derivative commodity instruments
Nonmonetary notional amount	60
Net commodity sale contracts \| Heating oil
Derivative commodity instruments
Nonmonetary notional amount \| gal	3	7
Foreign currencies
Derivative commodity instruments
Notional amounts \| $	$ 80	$ 82

Aggregate notional amount specified by the derivative(s). Expressed as an absolute value.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Article 12
-Section 13
-Sentence Column B

+ Details

Name:	invest_DerivativeNotionalAmount
Namespace Prefix:	invest_
Data Type:	xbrli:monetaryItemType
Balance Type:	na
Period Type:	instant

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_DerivativeLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Nominal mass used to calculate payments on a derivative instrument.

+ References

No definition available.

+ Details

Name:	us-gaap_DerivativeNonmonetaryNotionalAmountMass
Namespace Prefix:	us-gaap_
Data Type:	num:massItemType
Balance Type:	na
Period Type:	duration

- Definition

Nominal volume used to calculate payments on a derivative instrument.

+ References

No definition available.

+ Details

Name:	us-gaap_DerivativeNonmonetaryNotionalAmountVolume
Namespace Prefix:	us-gaap_
Data Type:	num:volumeItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_FutureMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=seb_CommodityPurchaseContractMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_TradingActivityByTypeAxis=seb_GrainMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_TradingActivityByTypeAxis=seb_SoybeanOilMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=seb_CommoditySaleContractMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_TradingActivityByTypeAxis=seb_HogsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_TradingActivityByTypeAxis=us-gaap_HeatingOilMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=us-gaap_ForeignExchangeContractMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: