Premises and Equipment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Premises and equipment
Premises and equipment, gross	$ 189,258	$ 194,909
Less: accumulated depreciation and amortization	141,203	140,949
Total	48,055	53,960
Depreciation and amortization expense	17,500	18,300	$ 16,500
Reduction in premises and equipment costs	14,300
Written off of leasehold assets	1,444	7,492
Furniture, fixtures and equipment
Premises and equipment
Premises and equipment, gross	145,615	149,366
Leasehold improvements
Premises and equipment
Premises and equipment, gross	$ 43,643	$ 45,543