Pension (Projected Benefit Obligation and Fair Value of Assets) (Details) - Pension Plan - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Change in projected benefit obligation:
Benefit obligation, beginning of year	$ 364,809	$ 361,778
Service cost	5,001	4,943	$ 7,330
Interest cost	16,536	17,557	19,047
Exchange rate fluctuations	1,214	(5,821)
Actuarial (gain) loss	24,400	8,631
Settlements paid	(281)	(259)
Benefits paid	(25,659)	(22,020)
Benefit obligation, end of year	386,020	364,809	361,778
Change in fair value of plan assets:
Fair value of plan assets, beginning of year	318,414	316,184
Actual return on plan assets	47,595	20,974
Employer contributions	3,150	3,535
Settlements paid	(281)	(259)
Benefits paid	(25,659)	(22,020)
Fair value of plan assets, end of year	$ 343,219	$ 318,414	316,184
Funded status of plan:
Funded ratio	88.90%	87.30%
Funded status and net accrued pension benefit cost	$ (42,801)	$ (46,395)
U.S. Plans
Change in projected benefit obligation:
Benefit obligation, beginning of year	336,648	325,863
Service cost	3,916	3,717	4,365
Interest cost	13,787	14,963	14,715
Exchange rate fluctuations	0	0
Actuarial (gain) loss	22,991	11,108
Settlements paid	(281)	(259)
Benefits paid	(23,008)	(18,744)
Benefit obligation, end of year	354,053	336,648	325,863
Change in fair value of plan assets:
Fair value of plan assets, beginning of year	318,414	316,184
Actual return on plan assets	47,595	20,974
Employer contributions	499	259
Settlements paid	(281)	(259)
Benefits paid	(23,008)	(18,744)
Fair value of plan assets, end of year	$ 343,219	$ 318,414	316,184
Funded status of plan:
Funded ratio	96.90%	94.60%
Funded status and net accrued pension benefit cost	$ (10,834)	$ (18,234)
Non-U.S. Plans
Change in projected benefit obligation:
Benefit obligation, beginning of year	28,161	35,915
Service cost	1,085	1,226	2,965
Interest cost	2,749	2,594	4,332
Exchange rate fluctuations	1,214	(5,821)
Actuarial (gain) loss	1,409	(2,477)
Settlements paid	0	0
Benefits paid	(2,651)	(3,276)
Benefit obligation, end of year	31,967	28,161	35,915
Change in fair value of plan assets:
Fair value of plan assets, beginning of year	0	0
Actual return on plan assets	0	0
Employer contributions	2,651	3,276
Settlements paid	0	0
Benefits paid	(2,651)	(3,276)
Fair value of plan assets, end of year	$ 0	$ 0	$ 0
Funded status of plan:
Funded ratio	0.00%	0.00%
Funded status and net accrued pension benefit cost	$ (31,967)	$ (28,161)

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.

Name:	us-gaap_DefinedBenefitPlanActualReturnOnPlanAssets
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of gain (loss) from change in actuarial assumptions which (increases) decreases benefit obligation of defined benefit plan. Assumptions include, but are not limited to, interest, mortality, employee turnover, salary, and temporary deviation from substantive plan.