Pension and Postretirement Benefits - Summary of Funded Status of the Plans (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Domestic Plans
Change in plan assets:
Fair value of plan assets at beginning of year	$ 11,590
Fair value of plan assets at end of year	10,299	$ 11,590
Foreign Pension Plans
Change in benefit obligation:
Service cost	552	530	$ 488
Interest cost	381	492	488
Actuarial adjustments	(238)	(106)	158
Change in plan assets:
Fair value of plan assets at beginning of year	9,493
Fair value of plan assets at end of year	8,243	9,493
Foreign Pension Plans \| Funded Plans
Change in benefit obligation:
Benefit obligation at beginning of year	9,521	10,488
Service cost	552	530
Interest cost	308	406
Actuarial adjustments	(809)	658
Benefits paid	(732)	(3,231)
Translation adjustment	(706)	670
Benefit obligation at end of year	8,134	9,521	10,488
Change in plan assets:
Fair value of plan assets at beginning of year	9,493	10,576
Actual return on plan assets	(322)	764
Company contributions	514	710
Benefits paid	(732)	(3,231)
Translation adjustment	(710)	674
Fair value of plan assets at end of year	8,243	9,493	10,576
Funded status at end of year	109	(28)
Foreign Pension Plans \| Unfunded Pension Plans
Change in benefit obligation:
Benefit obligation at beginning of year	2,582	2,486
Interest cost	73	87
Actuarial adjustments	(25)	(54)
Benefits paid	(184)	(182)
Translation adjustment	(156)	245
Benefit obligation at end of year	2,290	2,582	2,486
Change in plan assets:
Company contributions	184	182
Benefits paid	(184)	(182)
Funded status at end of year	(2,290)	(2,582)
Pension Plans \| Domestic Plans
Change in benefit obligation:
Service cost	64	64	98
Interest cost	780	803	1,032
Actuarial adjustments	(76)	114	1
Pension Plans \| Domestic Plans \| Funded Plans
Change in benefit obligation:
Benefit obligation at beginning of year	15,440	15,027
Interest cost	481	492
Actuarial adjustments	(887)	618
Benefits paid	(799)	(697)
Benefit obligation at end of year	14,235	15,440	15,027
Change in plan assets:
Fair value of plan assets at beginning of year	11,590	10,416
Actual return on plan assets	(1,043)	855
Company contributions	551	1,016
Benefits paid	(799)	(697)
Fair value of plan assets at end of year	10,299	11,590	10,416
Funded status at end of year	(3,936)	(3,850)
Pension Plans \| Domestic Plans \| Unfunded Pension Plans
Change in benefit obligation:
Benefit obligation at beginning of year	9,857	9,825
Service cost	64	64
Interest cost	299	311
Actuarial adjustments	(425)	175
Benefits paid	(524)	(518)
Benefit obligation at end of year	9,271	9,857	9,825
Change in plan assets:
Company contributions	524	518
Benefits paid	(524)	(518)
Funded status at end of year	(9,271)	(9,857)
Postretirement Benefit Plans \| Domestic Plans
Change in benefit obligation:
Benefit obligation at beginning of year	13,807	13,619
Service cost	80	92	99
Interest cost	449	413	573
Actuarial adjustments	170	237	(790)
Plan amendments		816
Benefits paid	(1,052)	(1,370)
Benefit obligation at end of year	13,454	13,807	$ 13,619
Change in plan assets:
Company contributions	1,052	1,370
Benefits paid	(1,052)	(1,370)
Funded status at end of year	$ (13,454)	$ (13,807)

Amount of increase (decrease) in plan assets of defined benefit plan from actual return (loss) determined by change in fair value of plan assets adjusted for contributions, benefit payments, and other expenses.

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Amount of actuarial present value of benefits attributed to service rendered by employee for defined benefit plan.

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Amount of payment to participant of defined benefit plan which decreases benefit obligation. For pension plan, payment includes, but is not limited to, pension benefits and death benefits. For other postretirement plan, payment includes, but is not limited to, prescription drug benefits, health care benefits, life insurance benefits, and legal, educational and advisory services.

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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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Amount of contribution received by defined benefit plan from employer which increases plan assets.

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Amount of asset segregated and restricted to provide benefit under defined benefit plan. Asset includes, but is not limited to, stock, bond, other investment, earning from investment, and contribution by employer and employee.

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Amount of foreign currency translation gain (loss) which (increases) decreases benefit obligation of defined benefit plan.

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Amount of funded (unfunded) status of defined benefit plan, measured as difference between fair value of plan assets and benefit obligation. Includes, but is not limited to, overfunded (underfunded) status.

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Amount of cost recognized for passage of time related to defined benefit plan.

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Amount of payment to participant under defined benefit plan which decreases plan assets. For pension plan, payment includes, but is not limited to, pension benefits and death benefits. For other postretirement plan, payment includes, but is not limited to, prescription drug benefits, health care benefits, life insurance benefits, and legal, educational and advisory services.

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Amount of cost for actuarial present value of benefits attributed to service rendered by employee for defined benefit plan.

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Amount, after tax, of reclassification adjustment from accumulated other comprehensive income (loss) for gain (loss) of defined benefit plan.

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