Premises and Equipment - Bank Premises and Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Property, Plant and Equipment [Line Items]
Gross		$ 302,152
Lease right-of-use assets	$ 84,754
Gross	418,270
Accumulated depreciation	(108,573)
Accumulated depreciation		(92,984)
Net	309,697
Net	309,697	209,168
Premises
Property, Plant and Equipment [Line Items]
Gross	233,345	218,730
Leasehold improvements
Property, Plant and Equipment [Line Items]
Gross	13,582	10,241
Furniture and equipment
Property, Plant and Equipment [Line Items]
Gross	61,380	52,043
Computer equipment
Property, Plant and Equipment [Line Items]
Gross	25,062	20,972
Autos
Property, Plant and Equipment [Line Items]
Gross	$ 147	$ 166