Employee Post-Retirement Benefits (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended	6 Months Ended
Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Components of net periodic benefit cost
Service cost	$ 150	$ 127	$ 300	$ 254
Interest cost	188	200	376	400
Expected return on plan assets	0	0	0	0
Amortization of transition obligation	15	15	30	30
Amortization of prior service cost	(19)	(14)	(38)	(28)
Recognized net actuarial loss	135	107	270	214
Net periodic benefit cost	469	435	938	870
Employer's contribution for current premium:
Defined Benefit Plan Payments Made By Employer			168
Expected contributions for remainder of current year	169		169
Estimated Employer Contributions For Current Fiscal Year			$ 337

Total employer contributions to the plan paid in the current reporting period.

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Total estimated employer contributions for current premium for the current fiscal year.

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The amount of the prior service cost or credit recognized in net periodic benefit cost relating to benefit changes attributable to plan participants' prior service pursuant to a plan amendment or a plan initiation.

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The amount of the transition obligation or asset recognized in net periodic benefit cost.

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The employer's best estimate, as soon as it can be reasonably determined, of contributions expected to be paid to the plan in the current remaining fiscal period. Estimated contributions may be presented in the aggregate combining (1) contributions required by funding regulations or laws, (2) discretionary contributions, and (3) noncash contributions.

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An amount calculated as a basis for determining the extent of delayed recognition of the effects of changes in the fair value of assets. The expected return on plan assets is determined based on the expected long-term rate of return on plan assets and the market-related value of plan assets.

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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 total amount of net periodic benefit cost for defined benefit plans for the period. Periodic benefit costs include the following components: service cost, interest cost, expected return on plan assets, gain (loss), prior service cost or credit, transition asset or obligation, and gain (loss) due to settlements or curtailments.

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Amount of other defined benefit plan costs.

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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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