Consolidated Statements of Comprehensive Income (Unaudited) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Consolidated Statements of Comprehensive Income [Abstract]
Net income	$ 7,037	$ 6,532	$ 19,356	$ 19,842
Securities available for sale:
Unrealized holding gains on securities	2,486	7,963	4,594	22,618
Non-credit related portion of other-than-temporary impairment on securities				(9,376)
Reclassification adjustment for gains realized in net income		(3,113)	(1,095)	(2,961)
Amortization of unrealized holding gains on securities transferred to the held to maturity category	(83)	(121)	(276)	(511)
Total securities available for sale	2,403	4,729	3,223	9,770
Derivative instruments:
Unrealized holding losses on derivative instruments	(241)		(1,379)
Reclassification adjustment for gains realized in net income	(71)	(95)	(259)	(282)
Totals derivative instruments	(312)	(95)	(1,638)	(282)
Defined benefit pension and post-retirement benefit plans:
Net (loss) gain arising during the period
Less amortization of net actuarial loss recognized in net periodic pension cost	66	69	198	206
Total defined benefit pension and post-retirement benefit plans	66	69	198	206
Other comprehensive income, net of tax	2,157	4,703	1,783	9,694
Comprehensive income	$ 9,194	$ 11,235	$ 21,139	$ 29,536