Consolidated Statement of Shareholders' Equity - USD ($) $ in Thousands	Total	Common Stock Including APIC [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]
Balance at Dec. 31, 2012	$ 729,627	$ 356,571	$ 382,347	$ (9,291)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Comprehensive Income (Loss), Net of Tax, Attributable to Parent	63,471	0		2,933
Net Income (Loss) Attributable to Parent	60,538		60,538
Dividends, Common Stock, Cash	(49,204)	0	(49,204)	0
Tax expense from employee stock option plan	(242)	(242)	0	0
Stock Issued During Period, Value, Share-based Compensation, Forfeited	2,169	2,169	0	0
Stock Issued During Period, Value, New Issues	6,051	6,051	0	0
Balance at Dec. 31, 2013	751,872	364,549	393,681	(6,358)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Comprehensive Income (Loss), Net of Tax, Attributable to Parent	54,974	0		(3,718)
Net Income (Loss) Attributable to Parent	58,692		58,692
Dividends, Common Stock, Cash	(50,093)	0	(50,093)	0
Tax expense from employee stock option plan	(117)	(117)	0	0
Stock Issued During Period, Value, Share-based Compensation, Forfeited	1,646	1,646	0	0
Stock Issued During Period, Value, New Issues	9,039	9,039	0	0
Balance at Dec. 31, 2014	767,321	375,117	402,280	(10,076)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Comprehensive Income (Loss), Net of Tax, Attributable to Parent	56,617	0		2,914
Net Income (Loss) Attributable to Parent	53,703		53,703
Dividends, Common Stock, Cash	(50,993)	0	(50,993)	0
Tax expense from employee stock option plan	(118)	(118)	0	0
Stock Issued During Period, Value, Share-based Compensation, Forfeited	3,277	3,277	0	0
Stock Issued During Period, Value, New Issues	4,868	4,868	0	0
Balance at Dec. 31, 2015	$ 780,972	$ 383,144	$ 404,990	$ (7,162)