Commitments and Contingent Liabilities (Details) (USD $)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010
Commitments and Contingent Liabilities [Abstract]
Percentage of the Company's loans secured by real estate (in hundredths)	58.00%
Guarantor Obligations [Line Items]
Loans serviced by the Company for unrelated third parties	$ 301,900,000	$ 323,200,000
Standby Letters of Credit [Member]
Guarantor Obligations [Line Items]
Obligation instrument term	five years or less and expire unused
Commitments - maximum potential obligation	26,783,000	26,193,000
Commercial Letters of Credit [Member]
Guarantor Obligations [Line Items]
Commitments - maximum potential obligation	15,218,000	16,255,000
Unused lines of Credit [Member]
Guarantor Obligations [Line Items]
Commitments - maximum potential obligation	161,551,000	141,579,000
Commitment To Extend Credits Credit [Member]
Guarantor Obligations [Line Items]
Commitments - maximum potential obligation	603,322,000	501,987,000
Loans Sold With Recourse [Member]
Guarantor Obligations [Line Items]
Commitments - maximum potential obligation	$ 16,175,000	$ 13,970,000