Premises and Equipment (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Property, Plant and Equipment [Abstract]
Capital lease obligations	$ 1,500	$ 1,600
Operating leases, rent expense	22,000	21,400	$ 23,100
Depreciation and amortization expense	42,200	37,100	35,300
Premises and equipment transferred to other properties held for sale	$ 3,283	$ 25,231	$ 2,340