Summary Of Accounting Policies (Narrative) (Details) (USD $)	12 Months Ended
	Dec. 31, 2011 years	Dec. 31, 2010	Dec. 31, 2009
Due from the federal reserve	$ 1,013,051,000	$ 677,525,000
Due from certificates of deposit	$ 151,000,000	$ 171,100,000
Dilutive effect of common stock issuable upon the exercise of options, shares	275,522	240,673	301,902
Anti-dilutive shares	879,588	1,081,564	896,621
Other intangible assets amortization period	17
Bank Premises [Member]
Property, plant and equipment depreciation period, minimum	15
Property, plant and equipment depreciation period, maximum	40
Equipment [Member]
Property, plant and equipment depreciation period, minimum	3
Property, plant and equipment depreciation period, maximum	20