Premises and Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Property, Plant and Equipment
Premises and equipment, gross	$ 332,674	$ 324,907
Less accumulated depreciation	(141,862)	(129,695)
Premises and equipment, net	190,812	195,212
Land
Property, Plant and Equipment
Premises and equipment, gross	37,999	40,620
Buildings and improvements
Property, Plant and Equipment
Premises and equipment, gross	213,321	209,328
Furniture and equipment
Property, Plant and Equipment
Premises and equipment, gross	$ 81,354	$ 74,959