Premises and Equipment (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Property, Plant and Equipment [Line Items]
Right-of-use lease assets	$ 27,835	$ 31,348
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]	Total premises and equipment, net	Total premises and equipment, net
Accumulated depreciation and amortization	$ (148,486)	$ (140,450)
Total premises and equipment, net	427,540	441,692
Land
Property, Plant and Equipment [Line Items]
Premises and equipment	89,950	90,953
Buildings and improvements
Property, Plant and Equipment [Line Items]
Premises and equipment	289,701	293,338
Furniture, fixtures and equipment
Property, Plant and Equipment [Line Items]
Premises and equipment	100,889	100,863
Software
Property, Plant and Equipment [Line Items]
Premises and equipment	65,136	64,877
Construction in progress
Property, Plant and Equipment [Line Items]
Premises and equipment	$ 2,515	$ 763