Consolidated Statement of Shareholders' Equity (USD $) In Thousands	Total	Common Stock [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]
Beginning balance at Dec. 31, 2008	$ 628,373	$ 336,754	$ 296,005	$ (4,386)
Other Comprehensive Income (Loss), Net of Tax	73,540		75,122	(1,582)
Restricted stock amortizations	39	39
Dividends paid on common stock	(42,415)		(42,415)
Tax benefit from employee stock option plan	229	229
Stock-based compensation	(776)	(776)
Issuance of common stock	1,115	1,115
Ending balance at Dec. 31, 2009	660,105	337,361	328,712	(5,968)
Other Comprehensive Income (Loss), Net of Tax	72,031		72,667	(636)
Dividends paid on common stock	(44,652)		(44,652)
Tax benefit from employee stock option plan	(125)	(125)
Stock-based compensation	554	554
Issuance of common stock	5,188	5,188
Ending balance at Dec. 31, 2010	693,101	342,978	356,727	(6,604)
Other Comprehensive Income (Loss), Net of Tax	62,702		63,898	(1,196)
Dividends paid on common stock	(46,690)		(46,690)
Tax benefit from employee stock option plan	(26)	(26)
Stock-based compensation	1,769	1,769
Issuance of common stock	3,632	3,632
Common Stock Expense	0	30	(30)
Ending balance at Dec. 31, 2011	$ 714,488	$ 348,383	$ 373,905	$ (7,800)