Premises, Furniture and Equipment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Property, Plant and Equipment [Line Items]
Total	$ 302,899	$ 289,543
Less accumulated depreciation	(105,341)	(102,125)
Premises, furniture and equipment, net	197,558	187,418
Depreciation expense	12,000	11,700	$ 11,100
Land and land improvements
Property, Plant and Equipment [Line Items]
Total	60,444	52,442
Buildings and building improvements
Property, Plant and Equipment [Line Items]
Total	176,838	170,160
Depreciation expense	6,200	5,800	5,200
Furniture and equipment
Property, Plant and Equipment [Line Items]
Total	65,617	66,941
Depreciation expense	$ 5,800	$ 6,000	$ 6,000