Premises and Equipment, Net (Summary of Premises and Equipment) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	$ 968,434	$ 913,959
Less: Accumulated depreciation and amortization	297,265	292,064
Total premises and equipment, net	671,169	621,895
Land
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	164,232	147,704
Buildings and leasehold improvements
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	586,968	555,636
Furniture, equipment, and computer software
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	201,055	203,657
Construction in progress
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	$ 16,179	$ 6,962