Commitments and Contingent Liabilities (Details) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Commitments and Contingent Liabilities [Abstract]
Percentage of the Company's loans secured by real estate (in hundredths)	59.00%
Guarantor Obligations [Line Items]
Loans serviced by the Company for unrelated third parties	$ 308,400,000	$ 301,900,000
Unused lines of Credit [Member]
Guarantor Obligations [Line Items]
Commitments - maximum potential obligation	163,626,000	161,551,000
Commitment to Extend Credits [Member]
Guarantor Obligations [Line Items]
Commitments - maximum potential obligation	678,093,000	603,322,000
Standby Letters of Credit [Member]
Guarantor Obligations [Line Items]
Commitments - maximum potential obligation	37,510,000	26,783,000
Obligation instrument term	five years or less and expire unused
Commercial Letters of Credit [Member]
Guarantor Obligations [Line Items]
Commitments - maximum potential obligation	16,607,000	15,218,000
Loans Sold with Recourse [Member]
Guarantor Obligations [Line Items]
Commitments - maximum potential obligation	$ 13,690,000	$ 16,175,000