Benefit Plans (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended	12 Months Ended
Mar. 31, 2013	Apr. 01, 2012	Dec. 31, 2012
Change in Projected Benefit Obligation
Projected benefit obligation, beginning of period	$ 19,761	$ 16,879	$ 16,879
Service cost	231	193	774
Interest cost	207	197	787
Plan amendments	0		569
Actuarial loss	0		945
Benefits paid	(78)		(193)
Projected benefit obligation, end of period	20,121		19,761
Change in Plan Assets
Plan assets at fair value, beginning of period	0	0	0
Company contributions	78		193
Benefits paid	(78)		(193)
Plan assets at fair value, end of period	0		0
Unfunded Status of the Plan	$ (20,121)		$ (19,761)

Amount of gain (loss) from a decision to temporarily deviate from the substantive plan, or from a change in benefit obligation or plan asset value from changes in actuarial assumptions, for example, but not limited to, interest, mortality, employee turnover or salary scale.

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1) For defined benefit pension plans, the benefit obligation is the projected benefit obligation, which is the actuarial present value as of a date of all benefits attributed by the pension benefit formula to employee service rendered prior to that date. 2) For other postretirement defined benefit plans, the benefit obligation is the accumulated postretirement benefit obligation, which is the actuarial present value of benefits attributed to employee service rendered to a particular date.

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The amount of payments made for which participants are entitled under a pension plan, including pension benefits, death benefits, and benefits due on termination of employment. Also includes payments made under a postretirement benefit plan, including prescription drug benefits, health care benefits, life insurance benefits, and legal, educational and advisory services. This item represents a periodic decrease to the plan obligations and a decrease to plan assets.

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-Glossary Postretirement Benefits

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The increase in the fair value of plan assets from contributions made by the employer.

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Assets, usually stocks, bonds, and other investments, that have been segregated and restricted (usually in a trust) to provide benefits, at their fair value as of the measurement date. Plan assets include amounts contributed by the employer (and by employees for a contributory plan) and amounts earned from investing the contributions, less benefits paid. If a plan has liabilities other than for benefits, those non-benefit obligations may be considered as reductions of plan assets.

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The funded status is measured as the difference between the fair value of plan assets and the benefit obligation. Will normally be the same as the net Defined Benefit Plan, Amounts Recognized in Balance Sheet, Total.

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The increase in a defined benefit pension plan's projected benefit obligation or a defined benefit postretirement plan's accumulated postretirement benefit obligation due to the passage of time.

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The amount of increase or decrease due to a change in the terms of an existing plan or the initiation of a new plan. A plan amendment may increase or decrease benefits, including those attributed to years of service already rendered.

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The actuarial present value of benefits attributed by the pension benefit formula to services rendered by employees during the period. The portion of the expected postretirement benefit obligation attributed to employee service during the period. The service cost component is a portion of the benefit obligation and is unaffected by the funded status of the plan.

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