Premises and Equipment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Premises and equipment
Premises and equipment, gross	$ 210,210	$ 201,112
Less: accumulated depreciation and amortization	150,877	145,616
Total	59,333	55,496
Depreciation and amortization expense	16,500	16,300	$ 19,200
Reduction in premises and equipment costs	10,200
Reduction in accumulated depreciation and amortization	9,800
Furniture, fixtures and equipment
Premises and equipment
Premises and equipment, gross	157,770	154,202
Leasehold improvements
Premises and equipment
Premises and equipment, gross	$ 52,440	$ 46,910