Premises and Equipment (Summary of Premises and Equipment) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2020 USD ($) banking_center	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Property, Plant and Equipment [Abstract]
Land	$ 9,436	$ 10,997
Buildings and improvements	70,195	77,892
Leasehold improvements	71,332	77,346
Fixtures and equipment	73,730	73,946
Data processing and software	270,780	263,445
Total premises and equipment	495,473	503,626
Less: Accumulated depreciation and amortization	(396,211)	(388,562)
Property and equipment, net	99,262	115,064
Net Investment in Lease	127,481	155,349
Premises and equipment, net	226,743	270,413
Depreciation and amortization	32,500	$ 33,700	$ 34,900
Leased assets impairment loss	$ 12,000
Leased banking centers closed | banking_center	21