Bank Premises and Equipment - Summary of Bank Premises and Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Property, Plant and Equipment [Line Items]
Cost	$ 93,511	$ 81,395
Accumulated Depreciation & Amortization	(38,932)	(36,309)
Net Carrying Value	54,579	45,086
Premises [Member]
Property, Plant and Equipment [Line Items]
Cost	66,965	59,471
Accumulated Depreciation & Amortization	(21,298)	(20,260)
Net Carrying Value	45,667	39,211
Furniture and Fixtures [Member]
Property, Plant and Equipment [Line Items]
Cost	26,546	21,924
Accumulated Depreciation & Amortization	(17,634)	(16,049)
Net Carrying Value	$ 8,912	$ 5,875