Premises and Equipment - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Depreciation expense	$ 14,358	$ 13,136	$ 12,066
Rental expense	6,157	$ 4,827	$ 4,460
Future minimum payments due	45,159
Brand Group Holdings, Inc.
Property, Plant and Equipment [Line Items]
Rental expense	638
Future minimum payments due	$ 10,078