Consolidated Statements of Shareholders' Equity - USD ($) $ in Thousands	Total	Common Stock	Treasury Stock	Capital in Excess of Par Value	Retained Deficit	Accumulated Other Comprehensive Loss (note 14)
Balance, value at Dec. 31, 2012	$ 24,476	$ 209	$ 0	$ 313,377	$ (148,070)	$ (141,040)
Balance, shares at Dec. 31, 2012		20,835,489	0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	28,459				28,459
Other comprehensive income (loss)	67,880					67,880
Stock compensation expense (note 12)	5,063			5,063
Stock issued, value	5,382	$ 4		5,378
Stock issued, shares		(480,991)
Stock withheld for employee taxes	(451)			(451)
Balance value at Dec. 31, 2013	130,809	$ 213	$ 0	323,367	(119,611)	(73,160)
Balance, shares at Dec. 31, 2013		21,316,480	0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	4,963				4,963
Other comprehensive income (loss)	(65,287)					(65,287)
Stock compensation expense (note 12)	3,932			3,932
Stock issued, value	4,414	$ 5		4,409
Stock issued, shares		(527,371)
Stock withheld for employee taxes	(317)			(317)
Purchase of treasury shares, value	(1,060)		$ (1,060)
Purchase of treasury shares, shares			34,985
Balance value at Dec. 31, 2014	77,454	$ 218	$ (1,060)	331,391	(114,648)	(138,447)
Balance, shares at Dec. 31, 2014		21,843,851	34,985
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	66,333				66,333
Other comprehensive income (loss)	18,215					18,215
Excess tax benefits from share-based compensation arrangements	2,797			2,797
Stock compensation expense (note 12)	5,873			5,873
Stock issued, value	3,378		$ 11,887	(8,509)
Stock issued, shares			(336,741)
Stock withheld for employee taxes	(796)			(796)
Dividends	(9,597)				(9,597)
Purchase of treasury shares, value	(15,275)		$ (15,275)
Purchase of treasury shares, shares			412,473
Balance value at Dec. 31, 2015	$ 148,382	$ 218	$ (4,448)	$ 330,756	$ (57,912)	$ (120,232)
Balance, shares at Dec. 31, 2015		21,843,851	110,717