Retirement Plans (Changes in the Projected Benefit Obligation and Plan Assets) (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Pension Plan
Projected benefit obligation:
Benefit obligation at beginning of year	$ 119,873	$ 129,160
Service cost	1,041	1,021	$ 944
Interest cost	5,335	5,242	5,167
Net actuarial loss (gain)	2,684	(10,837)
Benefits paid	(4,965)	(4,713)
Benefit obligation at end of year	123,968	119,873	129,160
Fair value of plan assets:
Fair value of plan assets at beginning of year	126,930	130,775
Actual return on plan assets	10,786	868
Employer contributions	0	0
Benefits paid	(4,965)	(4,713)
Fair value of plan assets at end of year	132,751	126,930	130,775
Funded (unfunded) status at December 31	8,783	7,057
Accumulated benefit obligation	115,418	109,583
Postretirement Plan
Projected benefit obligation:
Benefit obligation at beginning of year	3,247	3,702
Service cost	9	16	18
Interest cost	132	133	142
Net actuarial loss (gain)	(478)	(363)
Benefits paid	(309)	(241)
Benefit obligation at end of year	2,601	3,247	3,702
Fair value of plan assets:
Fair value of plan assets at beginning of year	0	0
Actual return on plan assets	0	0
Employer contributions	309	241
Benefits paid	(309)	(241)
Fair value of plan assets at end of year	0	0	$ 0
Funded (unfunded) status at December 31	(2,601)	(3,247)
Accumulated benefit obligation	$ 2,601	$ 3,247

For defined benefit pension plans, the actuarial present value of benefits (whether vested or nonvested) attributed by the pension benefit formula to employee service rendered before a specified date and based on employee service and compensation (if applicable) before that date. The accumulated benefit obligation differs from the projected benefit obligation in that it includes no assumption about future compensation levels. For plans with flat-benefit or nonpay-related pension benefit formulas, the accumulated benefit obligation and the projected benefit obligation are the same.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Accumulated Benefit Obligation
-URI http://asc.fasb.org/extlink&oid=6503844

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-Name Accounting Standards Codification
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The difference between fair value of plan assets at the end of the period and the fair value at the beginning of the period, adjusted for contributions and payments of benefits during the period, and after adjusting for taxes and other expenses, as applicable.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
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-Glossary Actual Return on Plan Assets (Component of Net Periodic Postretirement Benefit Cost)
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Amount of gain (loss) related to change in benefit obligation resulting from changes in actuarial assumptions, for example, but not limited to, interest, mortality, employee turnover, salary, and temporary deviation from the substantive plan.

+ References

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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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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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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 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.

+ References

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