Notes Payable and Long-Term Debt (Details 2) (USD $)	12 Months Ended
Dec. 31, 2014
Notes Payable and Long-Term Debt
Adjusted leverage ratio, maximum	3.5
Minimum net worth base requirement	$ 1,870,445,000
Percentage of consolidated net income added to net worth base amount	25.00%
Maximum dividends per year	$ 25,000,000
Sum of subsidiary indebtedness and priority indebtedness as a percentage of consolidated tangible net worth, maximum	20.00%

Represents the maximum adjusted leverage ratio per the terms of the debt covenants.

No definition available.

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Namespace Prefix:	seb_
Data Type:	xbrli:pureItemType
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Period Type:	duration

- Definition

Represents the maximum amount of dividends that may be paid per year per the terms of the debt covenants.

+ References

No definition available.

+ Details

Name:	seb_DebtInstrumentCovenantDividendRestrictionMaximumAmount
Namespace Prefix:	seb_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Represents the base amount that is used in the calculation of minimum tangible net worth requirement per the terms of the debt covenants.

+ References

No definition available.

+ Details

Name:	seb_DebtInstrumentCovenantMinimumNetWorthRequirementBaseAmount
Namespace Prefix:	seb_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Represents the percentage of the consolidated net income that is used in the calculation of the minimum net worth requirement per the terms of the debt covenants.

+ References

No definition available.

+ Details

Name:	seb_DebtInstrumentCovenantPercentageOfConsolidatedNetIncomeAddedToMinimumNetWorthRequirement
Namespace Prefix:	seb_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Represents the maximum percentage of the sum of subsidiary indebtedness and priority indebtedness as a percentage of net worth allowed per the terms of the debt covenants.

+ References

No definition available.

+ Details

Name:	seb_DebtInstrumentCovenantSumOfSubsidiaryIndebtednessAndPriorityIndebtednessAsPercentageOfNetWorthMaximum
Namespace Prefix:	seb_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_DebtDisclosureAbstract
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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration