Goodwill and Other Intangible Assets (Details Textuals) - USD ($) $ in Thousands			3 Months Ended		9 Months Ended	12 Months Ended
	Jun. 30, 2020	Feb. 14, 2020	Sep. 30, 2020	Mar. 31, 2020	Sep. 30, 2020	Dec. 31, 2019
Goodwill and Intangible Assets Disclosure [Abstract]
Valuation Allowance for Impairment of Recognized Servicing Assets, Additions (Deductions) for Expenses (Recoveries)			$ 18,000		$ 18,481	$ 63
Goodwill [Line Items]
Goodwill			$ 1,107,902		1,107,902	1,176,230
Goodwill, Acquired During Period				$ 13,000
Other Intangibles
Goodwill [Line Items]
Decrease of other intangible assets					19,000
Other Intangibles | Disposal Group, Disposed of by Sale, Not Discontinued Operations [Member]
Goodwill [Line Items]
Decrease of other intangible assets					$ 17,435	$ 217
Other Intangibles | Disposal Group, Disposed of by Sale, Not Discontinued Operations [Member] | ABRC
Goodwill [Line Items]
Decrease of other intangible assets	$ (17,000)
First Staunton Bancshares [Member]
Goodwill [Line Items]
Goodwill, Acquired During Period	$ 82,000	$ 13,414		$ 15,000