Consolidated Statements of Stockholders' Equity (Unaudited) (USD $) In Thousands, except Share data	Total	Common Shares Outstanding	Shares Held in Rabbi Trust at Cost	Deferred Compensation Obligation	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive (Loss) Income
Beginning balance at Dec. 31, 2009	$ 412,649	$ 209	$ (2,482)	$ 2,482	$ 225,088	$ 184,599	$ 2,753
Beginning balance, shares at Dec. 31, 2009		21,072,196
COMPREHENSIVE INCOME:
Net Income	17,257					17,257
Change in Unrealized Gain on Securities Available For Sale, Net of Tax and Realized Gains/(Losses)							4,458
Change in Fair Value of Cash Flow Hedges, Net of Tax and Realized Gains/(Losses)							(5,784)
Amortization of Prior Service Cost, net of tax							46
Other Comprehensive Loss	(1,280)						(1,280)
TOTAL COMPREHENSIVE INCOME	15,977
DIVIDENDS DECLARED:
COMMON DIVIDEND DECLARED ($0.38 PER SHARE and $0.36 PER SHARE for 2011 & 2010 respectively)	(7,628)					(7,628)
PROCEEDS FROM EXERCISE OF STOCK OPTIONS	360	1				359
PROCEEDS FROM EXERCISE OF STOCK OPTIONS, shares		25,595
TAX BENEFIT RELATED TO EQUITY AWARD ACTIVITY	70				70
EQUITY BASED COMPENSATION	743				743
RESTRICTED STOCK AWARDS GRANTED, NET OF AWARDS	(109)				(109)
RESTRICTED STOCK AWARDS GRANTED, NET OF AWARDS, shares		103,843
DEFERRED COMPENSATION OBLIGATION			(129)	129
Ending balance at Jun. 30, 2010	422,062	210	(2,611)	2,611	225,792	194,587	1,473
Ending balance, shares at Jun. 30, 2010		21,201,634
Beginning balance at Dec. 31, 2010	436,472	210	(2,738)	2,738	226,708	210,320	(766)
Beginning balance, shares at Dec. 31, 2010	21,220,801	21,220,801
COMPREHENSIVE INCOME:
Net Income	22,308					22,308
Change in Unrealized Gain on Securities Available For Sale, Net of Tax and Realized Gains/(Losses)							439
Change in Fair Value of Cash Flow Hedges, Net of Tax and Realized Gains/(Losses)							(910)
Amortization of Prior Service Cost, net of tax							252
Other Comprehensive Loss	(219)						(219)
TOTAL COMPREHENSIVE INCOME	22,089
DIVIDENDS DECLARED:
COMMON DIVIDEND DECLARED ($0.38 PER SHARE and $0.36 PER SHARE for 2011 & 2010 respectively)	(8,140)					(8,140)
PROCEEDS FROM EXERCISE OF STOCK OPTIONS	(3,701)	(2)			(3,699)
PROCEEDS FROM EXERCISE OF STOCK OPTIONS, shares		(162,875)
TAX BENEFIT RELATED TO EQUITY AWARD ACTIVITY	253				253
EQUITY BASED COMPENSATION	1,352				1,352
RESTRICTED STOCK AWARDS GRANTED, NET OF AWARDS	(361)				(361)
RESTRICTED STOCK AWARDS GRANTED, NET OF AWARDS, shares		60,495
SHARES ISSUED UNDER DIRECT STOCK PURCHASE PLAN	262				262
SHARES ISSUED UNDER DIRECT STOCK PURCHASE PLAN, shares		10,018
DEFERRED COMPENSATION OBLIGATION			(119)	119
TAX BENEFIT RELATED TO DEFERRED COMPENSATION DISTRIBUTIONS	74				74
Ending balance at Jun. 30, 2011	$ 455,702	$ 212	$ (2,857)	$ 2,857	$ 231,987	$ 224,488	$ (985)
Ending balance, shares at Jun. 30, 2011	21,454,189	21,454,189