Premises and Equipment (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Property, Plant and Equipment [Line Items]
Total Premises and Equipment, Gross	$ 206,322	$ 175,569
Accumulated depreciation	(108,826)	(100,261)
Total Premises and Equipment, Net	97,496	75,308
Land [Member]
Property, Plant and Equipment [Line Items]
Total Premises and Equipment, Gross	27,402	21,749
Buildings [Member]
Property, Plant and Equipment [Line Items]
Total Premises and Equipment, Gross	110,380	91,920
Equipment [Member]
Property, Plant and Equipment [Line Items]
Total Premises and Equipment, Gross	$ 68,540	$ 61,900