Consolidated Statement of Changes in Shareholders' Equity (Unaudited) (USD $) In Thousands, except Share data	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Treasury Stock [Member]	Total
Balance at Dec. 31, 2010	$ 34,131	$ 225,543	$ 374,700	$ (9,340)	$ (17,776)	$ 607,258
Balance (in shares) at Dec. 31, 2010	33,318,943
Net income			34,146			34,146
Other comprehensive income, net of tax				18,796		18,796
Dividends declared:
Common, $0.48 per share			(16,853)			(16,853)
Common stock issued under Stock Plan, including tax benefits of $284	135	1,717				1,852
Common stock issued under Stock Plan, including tax benefits of $284 (in shares)	135,289
Stock-based compensation		2,292				2,292
Stock issued for acquisition	3,353	79,227				82,580
Stock issued for acquisition (in shares)	3,352,801
Balance at Jun. 30, 2011	$ 37,619	$ 308,779	$ 391,993	$ 9,456	$ (17,776)	$ 730,071
Balance (in shares) at Jun. 30, 2011	36,807,033