Premises and Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Property, Plant and Equipment
Premises and equipment, gross	$ 346,648	$ 332,674
Less accumulated depreciation	(152,191)	(141,862)
Premises and equipment, net	194,457	190,812
Land
Property, Plant and Equipment
Premises and equipment, gross	39,794	37,999
Buildings and improvements
Property, Plant and Equipment
Premises and equipment, gross	218,317	213,321
Furniture and equipment
Property, Plant and Equipment
Premises and equipment, gross	$ 88,537	$ 81,354