Fair Value Measurements (Details Textuals) (USD $)	6 Months Ended		12 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Dec. 31, 2010
Fair Value Measurements (Textuals) [Abstract]
Other real estate owned measured at fair value	$ 32,000,000		$ 55,000,000
Write down of Other Real Estate Owned	4,000,000	5,000,000	10,000,000
Notional amount of cash flow hedge interest rate swap agreements	200,000,000		200,000,000
Commitment on standby letters of credit	$ 300,000,000		$ 400,000,000