Consolidated Statements of Stockholders' Equity (Unaudited) (USD $) In Thousands	Common Stock [Member]	Additional Paid-in-Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Common Stock in Treasury [Member]	Total
Beginning Balance at Dec. 31, 2010	$ 380	$ 314,023	$ 299,797	$ (5,335)	$ (75,293)	$ 533,572
Net income	0	0	44,179	0	0	44,179
Cash dividends	0	0	(20,439)	0	0	(20,439)
Purchase of treasury stock	0	0	0	0	(30,502)	(30,502)
Net issuance of shares to employee benefit plans and other stock plans, including tax benefit	0	(420)	(137)	0	1,185	628
Stock-based compensation	0	2,436	0	0	0	2,436
Other comprehensive income	0	0	0	8,974	0	8,974
Ending Balance at Sep. 30, 2011	380	316,039	323,400	3,639	(104,610)	538,848
Beginning Balance at Dec. 31, 2011	380	317,329	329,981	(6,104)	(103,476)	538,110
Net income	0	0	41,442	0	0	41,442
Cash dividends	0	0	(19,966)	0	0	(19,966)
Purchase of treasury stock	0	0	0	0	(15,490)	(15,490)
Net issuance of shares for acquisition	13	25,811	0	0	0	25,824
Net issuance of shares to employee benefit plans and other stock plans, including tax benefit	0	(764)	(196)	0	1,785	825
Stock-based compensation	0	3,558	0	0	0	3,558
Other comprehensive income	0	0	0	2,358	0	2,358
Ending Balance at Sep. 30, 2012	$ 393	$ 345,934	$ 351,261	$ (3,746)	$ (117,181)	$ 576,661