| Accumulated Other Comprehensive  Income (Details 1) (USD $) In Thousands, unless otherwise specified | 3 Months Ended | |
|---|---|---|
| Mar. 30, 2013 | Mar. 31, 2012 | |
| Unrealized gains and losses on available-for-sale securities | ||
| Miscellaneous (income) expense, net | $ (94) | $ 125 | 
| Unrealized gains and losses on available-for-sale securities before tax | 14,154 | 15,741 | 
| Income Tax Expense (Benefit) | 4,579 | 5,118 | 
| Unrealized gains and losses on available-for-sale securities Net of Tax | 9,575 | 10,623 | 
| Reclassification out of Accumulated Other Comprehensive Income [Member] | ||
| Unrealized gains and losses on available-for-sale securities | ||
| Unrealized gains and losses on available-for-sale securities Net of Tax | (35) | |
| Unrealized gains and losses on available-for-sale securities [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member] | ||
| Unrealized gains and losses on available-for-sale securities | ||
| Unrealized gains and losses on available-for-sale securities before tax | (52) | |
| Income Tax Expense (Benefit) | 17 | |
| Unrealized gains and losses on available-for-sale securities Net of Tax | (35) | |
| Unrealized gains and losses on available-for-sale securities [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member] | Realized gain/(loss) on sale of securities [Member] | ||
| Unrealized gains and losses on available-for-sale securities | ||
| Miscellaneous (income) expense, net | 9 | |
| Unrealized gains and losses on available-for-sale securities [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member] | Other than temporary impairment [Member] | ||
| Unrealized gains and losses on available-for-sale securities | ||
| Miscellaneous (income) expense, net | $ (61) | |
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- Definition Sum of operating profit and nonoperating income or expense before Income or Loss from equity method investments, income taxes, extraordinary items, and noncontrolling interest. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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- Definition The sum of the current income tax expense or benefit and the deferred income tax expense or benefit pertaining to continuing operations. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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- Definition The portion of profit or loss for the period, net of income taxes, which is attributable to the parent. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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- Definition The aggregate amount of income or expense from ancillary business-related activities (that is to say, excluding major activities considered part of the normal operations of the business). Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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