Investments (Details) (USD $) In Thousands, unless otherwise specified	Apr. 04, 2015	Dec. 31, 2014
Investments
Total short term investments, amortized cost	$ 598,730seb_ShortTermInvestmentsAtAmortizedCost	$ 497,230seb_ShortTermInvestmentsAtAmortizedCost
Total short term investments, fair value	597,619us-gaap_ShortTermInvestments	490,566us-gaap_ShortTermInvestments
Estimated fair value of fixed rate securities designated as available-for-sale, classified by the contractual maturity date of the security
Due within one year	984
Due after one year through three years	11,077
Due after three years	12,093
Total fixed rate securities	24,154
Available-for-sale securities.
Investments
Amortized Cost	263,243	167,049
Fair Value	263,451	167,096
Money market funds
Investments
Amortized Cost	236,974	142,432
Fair Value	236,974	142,432
Corporate bonds
Investments
Amortized Cost	11,652	11,000
Fair Value	11,757	11,015
U.S. Government agency securities
Investments
Amortized Cost	9,287	9,684
Fair Value	9,354	9,666
Asset backed debt securities
Investments
Amortized Cost	2,521	2,260
Fair Value	2,554	2,291
U.S. Treasury securities
Investments
Amortized Cost	1,990	523
Fair Value	1,996	522
Collateralized mortgage obligations
Investments
Amortized Cost	819	1,150
Fair Value	816	1,170
Trading securities.
Investments
Amortized Cost	335,487	330,181
Fair Value	334,168	323,470
High yield debt securities
Investments
Amortized Cost	178,466	187,491
Fair Value	175,390	181,483
Equity mutual fund
Investments
Amortized Cost	86,309	83,809
Fair Value	86,268	82,542
Domestic equity ETF
Investments
Amortized Cost	59,157	31,307
Fair Value	61,806	32,651
Money market funds held in trading accounts
Investments
Amortized Cost	6,362	21,401
Fair Value	6,362	21,401
Emerging markets trading debt mutual fund
Investments
Amortized Cost	3,323	3,323
Fair Value	2,550	2,614
Other trading investments
Investments
Amortized Cost	1,870	2,850
Fair Value	1,792	2,779
Denominated in Canadian dollars \| Money market funds
Investments
Fair Value	2,849
Denominated in Euros \| Money market funds
Investments
Fair Value	$ 13,132

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Represents the fair value of debt securities which are expected to mature after one year and through three years from the balance sheet date and which are categorized neither as held-to-maturity nor trading securities.

+ References

No definition available.

+ Details

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- Definition

Represents the fair value of debt securities which are expected to mature after three years from the balance sheet date and which are categorized neither as held-to-maturity nor trading securities.

+ References

No definition available.

+ Details

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- Definition

This item represents a parenthetical disclosure of the amortized cost of securities classified as short-term investments.

+ References

No definition available.

+ Details

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- Definition

Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 25

-Paragraph 1

-Subparagraph (b)

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Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 50

-Paragraph 5

-Subparagraph (aa)

-URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27232-111563

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 45

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6871852&loc=d3e26610-111562

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- Definition

This item represents the cost of debt and equity securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any.

+ References

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