Pension and Other Post-retirement Benefit Plans (Details) (USD $)	3 Months Ended
Mar. 31, 2015	Mar. 31, 2014
Pension Benefits
Components of net periodic benefit cost:
Service cost	$ 182,000	$ 149,000
Interest cost	2,370,000	2,601,000
Expected return on plan assets	(3,309,000)	(3,201,000)
Amortization of:
Prior service cost (benefit)	77,000	79,000
Actuarial loss (gain)	941,000	643,000
Net periodic benefit cost (benefit)	261,000	271,000
Anticipated contributions	36,000,000
Contributions made	9,600,000
Contributions by employer	3,000,000
Pension Benefits \| Scenario, Previously Reported
Amortization of:
Anticipated contributions	10,800,000
Other Post-Retirement Benefits
Components of net periodic benefit cost:
Service cost	72,000	56,000
Interest cost	201,000	343,000
Amortization of:
Prior service cost (benefit)	(432,000)	(372,000)
Actuarial loss (gain)	(119,000)	(45,000)
Net periodic benefit cost (benefit)	(278,000)	(18,000)
Contributions made	500,000
Other Post-Retirement Benefits \| Scenario, Forecast
Amortization of:
Contributions made	2,600,000
Pension Benefit Guaranty Corporation \| Pension Benefits
Amortization of:
Contributions by employer	2,100,000
Pension Benefit Guaranty Corporation \| Pension Benefits \| Scenario, Previously Reported
Amortization of:
Anticipated contributions	$ 8,500,000

The amount of gains or losses recognized in net periodic benefit cost.

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- Definition

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.

+ References

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- Definition

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.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Postretirement Benefits

-URI http://asc.fasb.org/extlink&oid=6521376

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 60

-Section 50

-Paragraph 4

-URI http://asc.fasb.org/extlink&oid=6414203&loc=d3e39716-114964

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 30

-Glossary Benefits

-URI http://asc.fasb.org/extlink&oid=6506267

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-Publisher FASB

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- Definition

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

+ References

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- Definition

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.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 30

-Glossary Expected Return on Plan Assets

-URI http://asc.fasb.org/extlink&oid=6512136

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 60

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- Definition

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.

+ References

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- Definition

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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- Definition

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

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (h)(1)

-URI http://asc.fasb.org/extlink&oid=35743120&loc=d3e1928-114920

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-Publisher FASB

-Name Accounting Standards Codification

-Glossary Service Cost (Component of Net Periodic Pension Cost)

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-Publisher FASB

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-Subparagraph (a)(1)

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- Definition

Amount of employer's best estimate of contributions expected to be paid to the plan in the current remaining fiscal period.

+ References

No definition available.

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