Consolidated Statements of Shareholders' Equity (USD $) In Thousands	Total	Common Stock	Restricted Stock	Additional Paid-In Capital	Retained Earnings	Accumulated other Comprehensive Income(Loss)
Beginning Balance at Dec. 31, 2010	$ 451,470	$ 1	$ 11,008	$ 67,420	$ 371,626	$ 1,415
Beginning Balance (in shares) at Dec. 31, 2010		41,498	244
Net income	122,856				122,856
Other comprehensive loss, net of tax	(73,849)					(73,849)
Excess tax benefits on stock-based compensation plans, share		1
Excess tax benefits on stock-based compensation plans	2			2
Restricted stock activity (in shares)		72	(1)
Restricted stock activity	2,684		2,684
Dividends	(9,974)				(9,974)
Ending Balance at Dec. 31, 2011	493,189	1	13,692	67,422	484,508	(72,434)
Ending Balance (in shares) at Dec. 31, 2011		41,571	243
Net income	185,543				185,543
Other comprehensive loss, net of tax	(13,699)					(13,699)
Excess tax benefits on stock-based compensation plans	645		645
Restricted stock activity (in shares)		89	18
Restricted stock activity	3,725		3,725
Dividends	(103,733)				(103,733)
Ending Balance at Dec. 31, 2012	565,670	1	18,062	67,422	566,318	(86,133)
Ending Balance (in shares) at Dec. 31, 2012		41,660	261
Net income	219,658				219,658
Other comprehensive loss, net of tax	(68,170)					(68,170)
Excess tax benefits on stock-based compensation plans	656		656
Restricted stock activity (in shares)		97	(10)
Restricted stock activity	4,732		4,732
Dividends	0				0
Ending Balance at Dec. 31, 2013	$ 722,546	$ 1	$ 23,450	$ 67,422	$ 785,976	$ (154,303)
Ending Balance (in shares) at Dec. 31, 2013		41,757	251