Consolidated Statement of Stockholders' Equity - USD ($) $ in Thousands	Stockholders' Equity of the Company Common Stock [Member]	Stockholders' Equity of the Company Treasury Stock [Member]	Stockholders' Equity of the Company Additional Paid-in Capital [Member]	Accumulated Other Comprehensive Income (Loss)	Stockholders' Equity of the Company Retained Earnings [Member]	Noncontrolling Interest [Member]	Total
Common stock beginning balance, share at Dec. 31, 2017	45,862,000
Beginning balance, value at Dec. 31, 2017	$ 459	$ (615,677)	$ 351,725	$ (102,304)	$ 721,664	$ 6,978	$ 362,845
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income					4,591	1,341	5,932
Dividends to shareholders					(12,414)		(12,414)
Dividends distributed to noncontrolling interest						(945)	(945)
Foreign currency translation adjustments				(5,700)		101	(5,599)
Derivatives valuation, net of tax				(7)			(7)
Vesting of restricted stock units, share	117,000
Vesting of restricted stock units, value	$ 1	1,939	(3,662)				(1,722)
Equity-based compensation expense			3,609				3,609
Other, net of tax.				108			108
Common stock ending balance, share at Mar. 31, 2018	45,979,000
Ending balance, value at Mar. 31, 2018	$ 460	(613,738)	351,672	(107,903)	707,257	7,475	345,223
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative Effect of New Accounting Principle in Period of Adoption					(6,584)		$ (6,584)
Preferred stock beginning balance, share at Dec. 31, 2018							0
Common stock beginning balance, share at Dec. 31, 2018	46,195,000						46,194,717
Beginning balance, value at Dec. 31, 2018	$ 462	(610,177)	353,932	(124,596)	725,551	7,677	$ 352,849
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income					19,002	1,474	20,476
Dividends to shareholders					(13,864)		(13,864)
Capital contribution from noncontrolling interest						1,330	1,330
Dividends distributed to noncontrolling interest						(900)	(900)
Foreign currency translation adjustments				1,602		29	1,631
Derivatives valuation, net of tax				3,061			3,061
Vesting of restricted stock units, share	102,000
Vesting of restricted stock units, value	$ 1	1,687	(3,461)				(1,773)
Equity-based compensation expense			3,168				3,168
Other, net of tax.				55			$ 55
Preferred stock ending balance, share at Mar. 31, 2019							0
Common stock ending balance, share at Mar. 31, 2019	46,297,000						46,296,816
Ending balance, value at Mar. 31, 2019	$ 463	$ (608,490)	$ 353,639	$ (119,878)	729,930	$ 9,610	$ 365,274
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative Effect of New Accounting Principle in Period of Adoption					$ (759)		$ (759)