Goodwill and Other Intangible Assets (Core Deposit Intangibles) (Details) - Core Deposit Intangibles - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Finite-Lived Intangible Assets [Line Items]
Gross balance	$ 86,099,000	$ 86,099,000
Accumulated amortization	(79,722,000)	(76,088,000)
Net carrying balance	6,377,000	10,011,000
Impairment write-offs/write downs on the remaining core deposit intangibles	$ 0	$ 0	$ 0