Retirement Plans - Reconciliation of Benefit Obligation, Plan Assets, and Funded Status (Details 2) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Change in plan assets:
Ending Balance	$ 329,581	$ 329,078
United States Pension Plan of US Entity, Defined Benefit [Member]
Retirement Plans
Accumulated benefit obligation	284,365	264,828
Change in projected benefit obligation:
Beginning Balance	264,828	264,828	274,497
Service cost	192	2,435	2,735
Interest cost	12,214	11,046	11,935
Benefits paid	(19,021)	(13,526)
Actuarial loss (gain)	26,152	(5,473)
Loss due to curtailment		(4,151)
Ending Balance	284,365	264,828	264,828
Change in plan assets:
Accumulated benefit obligation	284,365	264,828
Beginning Balance	314,211	314,211	265,622
Actual return on assets	13,961	62,012
Company contributions	5,302	103
Benefits paid	(19,021)	(13,526)
Ending Balance	314,453	314,211	314,211
Funded status (plan assets less projected benefit obligations)	30,088	49,383
Foreign Pension Plans [Member]
Retirement Plans
Accumulated benefit obligation	16,168	15,150
Change in projected benefit obligation:
Beginning Balance	16,027	16,028	16,220
Service cost	83	110	125
Interest cost	608	536	571
Benefits paid	(1,024)	(1,297)
Actuarial loss (gain)	1,468	295
Foreign exchange impact and other	(995)	163
Ending Balance	16,168	16,027	16,028
Change in plan assets:
Accumulated benefit obligation	16,168	15,150
Beginning Balance	14,867	14,867	13,369
Actual return on assets	(2,258)	209
Company contributions	4,478	2,307
Benefits paid	(1,024)	(1,297)
Foreign exchange impact and other	(935)	279
Ending Balance	15,128	14,867	14,867
Funded status (plan assets less projected benefit obligations)	(1,040)	(1,160)
Other Postretirement Benefit Plan [Member]
Retirement Plans
Accumulated benefit obligation	5,194	4,916
Change in projected benefit obligation:
Beginning Balance	4,916	4,916	5,666
Service cost	4	7	9
Interest cost	230	223	255
Benefits paid	(179)	(182)
Actuarial loss (gain)	223	(798)
Ending Balance	5,194	4,916	4,916
Change in plan assets:
Accumulated benefit obligation	5,194	4,916
Company contributions	179	182
Benefits paid	(179)	(182)
Funded status (plan assets less projected benefit obligations)	$ (5,194)	$ (4,916)

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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.

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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.

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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.

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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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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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Amount of gain (loss) from foreign currency exchange rate changes for benefit obligation for plans of a foreign operation whose functional currency is not the reporting currency.

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The amount of increase or decrease in plan assets attributed to foreign currency changes. The effects of foreign currency exchange rate changes that are to be disclosed are those applicable to plans of a foreign operation whose functional currency is not the reporting currency.

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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 net gain (loss) recognized in net periodic benefit cost as a result of an event that significantly reduces the expected years of future service of present employees or eliminates for a significant number of employees the accrual of defined benefits for some or all of their future services.

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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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