Bank Premises and Equipment - Summary of Bank Premises and Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Property, Plant and Equipment [Line Items]
Cost	$ 101,843	$ 93,511
Accumulated Depreciation & Amortization	(43,159)	(38,932)
Net Carrying Value	58,684	54,579
Premises [Member]
Property, Plant and Equipment [Line Items]
Cost	71,562	66,965
Accumulated Depreciation & Amortization	(22,969)	(21,298)
Net Carrying Value	48,593	45,667
Furniture and Fixtures [Member]
Property, Plant and Equipment [Line Items]
Cost	30,281	26,546
Accumulated Depreciation & Amortization	(20,190)	(17,634)
Net Carrying Value	$ 10,091	$ 8,912