Premises and Equipment, Net (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 989,004	$ 873,040
Accumulated depreciation and amortization	(455,866)	(445,506)
Premises and equipment, net	533,138	427,534
Depreciation and amortization expense	75,300	48,600	$ 45,900
Land
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	151,332	144,754
Office buildings
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	334,673	268,495
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	59,141	51,868
Furniture, equipment and computer software
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	440,678	404,743
Premises and equipment leased under finance leases
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	3,180	$ 3,180
Premises and equipment, net	$ 289,700