Premises, Furniture, and Equipment - Narrative (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($) retail_branch
Property, Plant and Equipment [Abstract]
Number of branches sold | retail_branch			55
Pre-tax gain on sale-leaseback transaction			$ 88,000
Net gain on sale-leaseback transaction	$ 0	$ 0	5,509
Deferred gain, net	65,500	74,600
Depreciation of premises, furniture, and equipment	$ 15,865	$ 13,995	$ 12,804