Consolidated Statements Of Stockholders' Equity - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Retained Earnings	Accumulated Other Comprehensive Income	Noncontrolling Interest [Member]
Balance, beginning of year, shares at Dec. 31, 2017		1,886
Balance, beginning of year at Dec. 31, 2017	$ 177,921	$ 0	$ 161,891	$ 15,945	$ 85
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income attributable to the Company	21,757		21,757
Dividends paid	(2,264)		(2,264)
Shares of common stock repurchased and retired (in shares)		0
Shares of common stock repurchased and retired	(29)		(29)
Stock options and stock appreciation rights exercised (in shares)		1
Stock options and stock appreciation rights exercised	(1)		(1)
Share-based compensation expense related to stock appreciation rights	239		239
Cumulative effect adjustment for adoption of new accounting standards	0		13,627	(13,627)
Other comprehensive loss	(1,999)			(1,999)
Distribution of equity to noncontrolling interests	(52)				(52)
Net loss attributable to noncontrolling interests	(31)				(31)
Balance, end of year, shares at Sep. 30, 2018		1,887
Balance, end of year at Sep. 30, 2018	195,541	$ 0	195,220	319	2
Balance, beginning of year, shares at Jun. 30, 2018		1,887
Balance, beginning of year at Jun. 30, 2018	186,113	$ 0	185,252	806	55
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income attributable to the Company	10,634		10,634
Dividends paid	(755)		(755)
Shares of common stock repurchased and retired (in shares)		0
Shares of common stock repurchased and retired	0		0
Stock options and stock appreciation rights exercised (in shares)		0
Stock options and stock appreciation rights exercised	0		0
Share-based compensation expense related to stock appreciation rights	89		89
Cumulative effect adjustment for adoption of new accounting standards	0		0	0
Other comprehensive loss	(487)			(487)
Distribution of equity to noncontrolling interests	(52)				(52)
Net loss attributable to noncontrolling interests	(1)				(1)
Balance, end of year, shares at Sep. 30, 2018		1,887
Balance, end of year at Sep. 30, 2018	195,541	$ 0	195,220	319	2
Balance, beginning of year, shares at Dec. 31, 2018		1,887
Balance, beginning of year at Dec. 31, 2018	175,639	$ 0	174,690	949	0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income attributable to the Company	20,078		20,078
Dividends paid	(2,266)		(2,266)
Shares of common stock repurchased and retired (in shares)		0
Shares of common stock repurchased and retired	(11)		(11)
Stock options and stock appreciation rights exercised (in shares)		2
Stock options and stock appreciation rights exercised	0		0
Share-based compensation expense related to stock appreciation rights	204		204
Other comprehensive loss	2,246			2,246
Net loss attributable to noncontrolling interests	0
Balance, end of year, shares at Sep. 30, 2019		1,889
Balance, end of year at Sep. 30, 2019	195,890	$ 0	192,695	3,195	0
Balance, beginning of year, shares at Jun. 30, 2019		1,889
Balance, beginning of year at Jun. 30, 2019	188,295	$ 0	185,441	2,854	0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income attributable to the Company	7,952		7,952
Dividends paid	(755)		(755)
Shares of common stock repurchased and retired (in shares)		0
Shares of common stock repurchased and retired	0		0
Stock options and stock appreciation rights exercised (in shares)		0
Stock options and stock appreciation rights exercised	0		0
Share-based compensation expense related to stock appreciation rights	57		57
Other comprehensive loss	341			341
Net loss attributable to noncontrolling interests	0
Balance, end of year, shares at Sep. 30, 2019		1,889
Balance, end of year at Sep. 30, 2019	$ 195,890	$ 0	$ 192,695	$ 3,195	$ 0