CONSOLIDATED STATEMENT OF CHANGES IN SHAREHOLDERS' EQUITY (Unaudited) (USD $) In Thousands, except Share data, unless otherwise specified	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, 2014	$ 41,606	$ 409,984	$ 525,985	$ 30,720	$ (20,391)	$ 987,904
Balance (in shares) at Dec. 31, 2014	40,747,721
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income			22,297			22,297
Other comprehensive income, net of tax				18,213		18,213
Cash dividends declared:
Common, $0.30 per share			(12,226)			(12,226)
Common stock issued under employee stock plan, including tax benefits of $696	151	2,790				2,941
Common stock issued under employee stock plan, including tax benefits of $696 (in shares)	150,235
Stock-based compensation		1,151				1,151
Treasury stock purchased					(9,125)	(9,125)
Treasury stock purchased (in shares)	(265,230)					(265,230)
Treasury stock issued to benefit plan					2,247	2,247
Treasury stock issued to benefit plan (in shares)	91,549
Balance at Mar. 31, 2015	$ 41,757	$ 413,925	$ 536,056	$ 48,933	$ (27,269)	$ 1,013,402
Balance (in shares) at Mar. 31, 2015	40,724,275