Comprehensive Income (Schedule of Comprehensive Income) (Details) (USD $) In Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Comprehensive Income
Net income as reported	$ 8,632	$ 5,056	$ 14,411	$ 12,972
Net unrealized holding gain from available for sale securities arising during the period	6,467	3,610	8,780	7,166
Reclassification adjustment of net gain from sale of available for sale securities included in income	0	0	0	(38)
Net unrealized gain from securities, net of reclassification adjustment	6,467	3,610	8,780	7,128
Cash flow hedging instruments: Reclassification adjustment of net gain included in income	0	(248)	(143)	(727)
Net change in cash flow hedging instruments	0	(248)	(143)	(727)
Pension plan liability adjustment: Net unrealized gain from unfunded defined benefit plan liability arising during the period	0	0	(261)	23
Pension plan liability adjustment: Less: amortization of unrecognized net actuarial loss included in net periodic pension cost	14	7	28	14
Pension plan liability adjustment, net	14	7	(233)	37
Total comprehensive income	15,113	8,425	22,815	19,410
Net unrealized holding gain from available for sale securities arising during the period, tax	(3,641)	(1,907)	(4,925)	(3,943)
Reclassification adjustment of net gain from sale of available for sale securities included in income, tax	0	0	0	20
Cash flow hedging instruments: Reclassification adjustment of net gain included in income, tax	0	137	79	401
Net unrealized gain loss from unfunded defined benefit plan liability arising during period, tax	0	0	154	(12)
Amortization of unrecognized net actuarial loss included in net periodic pension cost, tax	$ (8)	$ (4)	$ (16)	$ (8)