Consolidated Statements of Changes in Stockholders' Equity (USD $) In Thousands	Common Stock [Member]	Additional Paid-in- Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive (Loss) Income [Member]	Common Stock in Treasury [Member]	Total
Balance at Dec. 31, 2008	$ 365	$ 276,418	$ 245,340	$ (8,204)	$ (82,074)	$ 431,845
Net income	0	0	52,011	0	0	52,011
Cash dividends	0	0	(27,119)	0	0	(27,119)
Net issuance of common shares	15	33,386	0	0	0	33,401
Net issuance of shares to employee stock plans, including tax benefit	0	(1,773)	0	0	4,258	2,485
Stock-based compensation	0	3,133	0	0	0	3,133
Other comprehensive income	0	0	0	9,367	0	9,367
Balance at Dec. 31, 2009	380	311,164	270,232	1,163	(77,816)	505,123
Net income	0	0	57,404	0	0	57,404
Cash dividends	0	0	(27,577)	0	0	(27,577)
Purchase of treasury shares	0	0	0	0	(477)	(477)
Net issuance of shares to employee stock plans, including tax benefit	0	(923)	(262)	0	3,000	1,815
Stock-based compensation	0	3,782	0	0	0	3,782
Other comprehensive income	0	0	0	(6,498)	0	(6,498)
Balance at Dec. 31, 2010	380	314,023	299,797	(5,335)	(75,293)	533,572
Net income	0	0	57,901	0	0	57,901
Cash dividends	0	0	(27,063)	0	0	(27,063)
Purchase of treasury shares	0	0	0	0	(30,502)	(30,502)
Net issuance of shares to employee stock plans, including tax benefit	0	62	(654)	0	2,319	1,727
Stock-based compensation	0	3,244	0	0	0	3,244
Other comprehensive income	0	0	0	(769)	0	(769)
Balance at Dec. 31, 2011	$ 380	$ 317,329	$ 329,981	$ (6,104)	$ (103,476)	$ 538,110