Segment information (Details Textuals) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Segment information (Textuals) [Abstract]
Taxable Equivalent Adjustment	$ 6,468,000	$ 6,105,000	$ 12,795,000	$ 12,028,000