Condensed Consolidated Statement of Shareholders' Equity - 6 months ended Jun. 30, 2018 - USD ($) $ in Thousands	Total	Common Stock	Unrecognized Gains (Losses) on Derivative Instruments	Pension Obligations	Cumulative Translation Adjustment	Retained Earnings	Non-controlling Interest
Beginning of period at Dec. 31, 2017	$ 445,723	$ 89,755	$ (8,498)	$ (5,257)	$ (75,366)	$ 393,146	$ 51,943
Beginning of the period (in shares) at Dec. 31, 2017	24,917,025	24,917,025
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	$ 18,452					18,452
Change in unrecognized gains (losses) on derivative instruments, net of tax	(4,079)		(4,079)
Change in employee benefit plans, net of taxes	131			131
Net foreign currency translation adjustment	(17,180)				(17,180)
Stock options exercised	$ 68	$ 68
Stock options exercised (in shares)	4,500	4,500
Restricted stock awards granted, net of forfeitures	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0
Restricted stock awards granted, net of forfeitures (in shares)		90,205
Stock-based compensation expense	$ 1,107	$ 1,107
Stock-based compensation expense (in shares)	0	0	0	0	0	0	0
Cash dividends declared	$ (4,845)					$ (4,845)
Redeemable preferred dividend and accretion	(16,204)					(16,204)
Reclassification to European non-controlling redeemable equity	(51,943)						$ (51,943)
Adjust European non-controlling redeemable equity to redemption value	(3,625)	$ (3,625)
European non-controllingredeemable equity translation adjustment	2,851					2,851
European non-controllingredeemable equity dividend	(1,084)					(1,084)
End of period at Jun. 30, 2018	$ 369,372	$ 87,305	$ (12,577)	$ (5,126)	$ (92,546)	$ 392,316
End of the period (in shares) at Jun. 30, 2018	25,011,730	25,011,730