This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. This item represents Available-for-sale Securities which consist of all investments in certain debt and equity securities neither classified as trading or held-to-maturity securities. A debt security represents a creditor relationship with an enterprise. Debt securities include, among other items, US Treasury securities, US government securities, municipal securities, corporate bonds, convertible debt, commercial paper, and all securitized debt instruments. An equity security represents an ownership interest in an enterprise or the right to acquire or dispose of an ownership interest in an enterprise at fixed or determinable prices. Equity securities include, among other things, common stock, certain preferred stock, warrant rights, call options, and put options, but do not include convertible debt. An entity may opt to provide the reader with additional narrative text to better understand the nature of investments in debt and equity securities which are categorized as Available-for-sale.

No definition available.

Investment Securities (Details Textual) - USD ($) $ in Thousands	3 Months Ended				9 Months Ended		12 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019	Jan. 01, 2020
Investment Securities Information [Line Items]
Debt Securities, AFS, Principal Sold		$ 261,000	$ 281,000
Gain (Loss) on Sales of Mortgage Backed Securities (MBS)		$ 3,000	$ 6,000
Debt Securities, Available-for-sale, Sold at Par Value						$ 1,200,000
Pledged Financial Instruments, Not Separately Reported, Securities	$ 1,800,000				$ 1,800,000		$ 2,600,000
Interest Receivable	91,612				91,612		91,196
Debt Securities, Held-to-maturity, Nonaccrual, Interest Income					0		0
Debt Securities, Held-to-maturity, Past Due	0				0
Held to maturity allowance for credit loss	70				70			$ 61
Federal Home Loan Bank Stock	82,000				82,000		149,000
Federal Reserve Bank Stock	87,000				87,000		78,000
Equity securities with readily determinable fair values, Fair Value	$ 2,000				$ 2,000		2,000
Visa Restricted Stock Owned. Total	77,996
Visa Restricted Stock Owned at Fair Value					77,000
Visa Restricted Stock Donated				42,039
Visa Restricted Stock Owned at Zero Cost			996
Equity securities	$ 13,000				$ 13,000		13,000
Available-for-sale Securities1						$ 692,000
First Staunton Bancshares [Member]
Investment Securities Information [Line Items]
Carrying amount of Securities Sold			$ 84,000
Held-to-maturity Securities [Member]
Investment Securities Information [Line Items]
Interest Receivable	13,000				13,000		16,000
Available-for-sale Securities [Member]
Investment Securities Information [Line Items]
Interest Receivable	9,000				9,000		10,000
Federal Home Loan Bank Certificates and Obligations (FHLB) [Member]
Investment Securities Information [Line Items]
Interest Receivable	1,000				1,000		2,000
Federal Reserve Bank Stock [Member]
Investment Securities Information [Line Items]
Interest Receivable	$ 149				$ 149		$ 0