Premises and Equipment - Bank Premises and Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Property, Plant and Equipment [Line Items]
Lease right-of-use assets	$ 66,023	$ 84,754
Gross	426,681	418,270
Accumulated depreciation	(126,185)	(108,573)
Net	300,496	309,697
Premises
Property, Plant and Equipment [Line Items]
Gross	250,313	233,345
Leasehold improvements
Property, Plant and Equipment [Line Items]
Gross	21,289	13,582
Furniture and equipment
Property, Plant and Equipment [Line Items]
Gross	64,798	61,380
Computer equipment
Property, Plant and Equipment [Line Items]
Gross	24,114	25,062
Autos
Property, Plant and Equipment [Line Items]
Gross	$ 144	$ 147