CONSOLIDATED STATEMENTS OF STOCKHOLDERS EQUITY (USD $) In Thousands	Total	Common Stock [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income/(Loss) [Member]
Beginning balance at Dec. 31, 2009	$ 638,228	$ 491,226	$ 120,612	$ 26,390
Beginning balance, shares at Dec. 31, 2009		106,263
Repurchase of common stock	(5,169)	(5,169)
Repurchase of common stock, Shares		(640)
Exercise of stock options	1,547	1,547
Exercise of stock options, shares		304
Tax benefit from exercise of stock options	425	425
Shares issued pursuant to stock-based compensation plan	2,197	2,197
Shares issued pursuant to stock-based compensation plan, shares		149
Cash dividends declared Common ($0.34 per share)	(36,103)		(36,103)
Net earnings	62,935		62,935
Other comprehensive income	(20,205)			(20,205)
Ending balance at Dec. 31, 2010	643,855	490,226	147,444	6,185
Ending balance, shares at Dec. 31, 2010		106,076
Repurchase of common stock	(12,527)	(12,527)
Repurchase of common stock, Shares		(1,595)
Exercise of stock options	59	59
Exercise of stock options, shares		9
Tax benefit from exercise of stock options	1	1
Shares issued pursuant to stock-based compensation plan	2,214	2,214
Shares issued pursuant to stock-based compensation plan, shares		(8)
Cash dividends declared Common ($0.34 per share)	(35,805)		(35,805)
Net earnings	81,733		81,733
Other comprehensive income	35,284			35,284
Ending balance at Dec. 31, 2011	714,814	479,973	193,372	41,469
Ending balance, shares at Dec. 31, 2011		104,482
Repurchase of common stock	(54)	(54)
Repurchase of common stock, Shares		(5)
Exercise of stock options	2,557	2,557
Exercise of stock options, shares	292	292
Tax benefit from exercise of stock options	194	194
Shares issued pursuant to stock-based compensation plan	2,039	2,039
Shares issued pursuant to stock-based compensation plan, shares		121
Cash dividends declared Common ($0.34 per share)	(35,642)		(35,642)
Net earnings	77,280		77,280
Other comprehensive income	1,782			1,782
Ending balance at Dec. 31, 2012	$ 762,970	$ 484,709	$ 235,010	$ 43,251
Ending balance, shares at Dec. 31, 2012		104,890