Bank Premises and Equipment Net Book Value (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Bank Premises and Equipment
Total bank premises and equipment	$ 99,614	$ 96,070
Accumulated depreciation	(45,998)	(42,583)
Bank premises and equipment, net	53,616	53,487
Land
Bank Premises and Equipment
Total bank premises and equipment	12,085	11,976
Building and premises
Bank Premises and Equipment
Total bank premises and equipment	61,451	58,607
Furniture, fixtures and equipment
Bank Premises and Equipment
Total bank premises and equipment	$ 26,078	$ 25,487