Commitments and Contingent Liabilities (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Minimum future rental payments:
2014		$ 8,033,000
2015		6,787,000
2016		4,847,000
2017		3,642,000
2018		3,111,000
Thereafter		13,105,000
Total minimum payments		39,525,000
Operating Leases, Rent Expense, Sublease Rentals		673,000	639,000	655,000
Operating Leases, Rent Expense, Net		8,500,000	4,500,000	4,600,000
Restructuring and Related Cost, Expected Cost Remaining	1,200,000
Commitments to Extend Credit [Member]
Minimum future rental payments:
Fair Value Disclosure, Off-balance Sheet Risks, Amount, Liability		1,370,000,000	888,500,000
Standby Letters of Credit [Member]
Minimum future rental payments:
Fair Value Disclosure, Off-balance Sheet Risks, Amount, Liability		36,700,000	19,500,000
Commercial Letter of Credit and other off-balance sheet liabilities [Member]
Minimum future rental payments:
Fair Value Disclosure, Off-balance Sheet Risks, Amount, Liability		2,700,000	46,000
Branch consolidation [Member]
Minimum future rental payments:
Increase (Decrease) in Restructuring Reserve		1,400,000
Restructuring and Related Cost, Accelerated Depreciation		1,400,000
Restructuring and Related Cost, Cost Incurred to Date		2,800,000
Restructuring and Related Cost, Expected Cost		$ 4,000,000