Business Combinations (Allocation of Purchase Price) (Details) - USD ($)				9 Months Ended
	Sep. 01, 2021	May 03, 2021	Mar. 01, 2020	Sep. 30, 2021	Dec. 31, 2020	Dec. 31, 2019
Consideration transferred:
Goodwill				$ 89,984,000	$ 74,135,000	$ 65,614,000
Sevier County Bancshares Inc [Member]
Assets:
Cash and cash equivalents	$ 84,313,000			84,313,000
Investment securities available-for-sale	64,219,000			63,605,000
Restricted investments	533,000			533,000
Loans	304,620,000			300,069,000
Allowance for loan losses	(3,644,000)
Premises and equipment	15,579,000			15,284,000
Core deposit intangible				1,550,000
Bank owned life insurance	7,116,000			7,116,000
Deferred tax asset, net	10,340,000			6,333,000
Interest Receivable	884,000			884,000
Other assets	920,000			648,000
Total assets acquired	484,880,000			480,335,000
Liabilities:
Deposits	435,036,000			435,036,000
Time deposit premium				888,000
Subordinated debt	2,500,000			2,500,000
Payables and other liabilities	5,563,000			5,678,000
Total liabilities assumed	443,099,000			444,102,000
Total fair value of net assets acquired	41,781,000			36,233,000
Cash consideration paid	$ 9,600,000			9,568,000
Common stock issued				42,254,000
Number of shares issued (in shares)	1,691,535
Business Combination, Consideration Transferred, Total				51,822,000
Assets:
Investment securities available-for-sale	$ (614,000)
Loans	(4,551,000)
Allowance for loan losses	3,644,000
Premises and equipment, net	(295,000)
Deferred tax asset, net	(4,007,000)
Core deposit intangible	1,550,000
Other assets	(272,000)
Total assets acquired	(4,545,000)
Liabilities:
Time deposit premium	888,000
Payables and other liabilities	115,000
Total liabilities assumed	1,003,000
Consideration transferred:
Aggregate fair value adjustments	(5,548,000)
Goodwill	$ 15,600,000			15,589,000
Fountain [Member]
Assets:
Cash and cash equivalents		$ 413,000		413,000
Leases		54,945,000		54,225,000
Allowance for loan losses		(1,796,000)
Intangibles				2,658,000
Other repossessed assets		319,000		319,000
Other assets		233,000		233,000
Total assets acquired		54,114,000		57,848,000
Liabilities:
Payables and other liabilities		683,000		454,000
Total liabilities assumed		683,000		454,000
Total fair value of net assets acquired		53,431,000		57,394,000
Cash consideration paid		14,000,000.0		59,794,000
Business Combination, Consideration Transferred, Total				59,794,000
Assets:
Leases		(720,000)
Allowance for loan losses		1,796,000
Intangibles		2,658,000
Total assets acquired		3,734,000
Liabilities:
Payables and other liabilities		(229,000)
Total liabilities assumed		(229,000)
Consideration transferred:
Aggregate fair value adjustments		3,963,000
Goodwill		$ 2,400,000		2,400,000
Progressive Financial Group Inc. [Member]
Assets:
Cash and cash equivalents			$ 55,971,000	55,971,000
Investment securities available-for-sale			27,054,000	27,257,000
Restricted investments			692,000	692,000
Loans			191,672,000	187,981,000
Allowance for loan losses			(2,832,000)
Premises and equipment			15,681,000	12,762,000
Bank owned life insurance			5,560,000	5,560,000
Deferred tax asset, net				1,006,000
Intangibles				2,497,000
Other real estate owned			3,695,000	1,733,000
Interest Receivable			1,061,000	781,000
Prepaids			375,000	201,000
Goodwill			231,000
Other assets			1,881,000	1,881,000
Total assets acquired			301,041,000	298,322,000
Liabilities:
Deposits			271,276,000	271,276,000
Time deposit premium				729,000
Payables and other liabilities			776,000	776,000
Total liabilities assumed			272,052,000	272,781,000
Total fair value of net assets acquired			28,989,000	25,541,000
Cash consideration paid			9,800,000	9,838,000
Common stock issued			$ 1,292,578	24,547,000
Number of shares issued (in shares)			1,292,578
Business Combination, Consideration Transferred, Total				34,385,000
Assets:
Investment securities available-for-sale			$ 203,000
Loans			(3,691,000)
Allowance for loan losses			2,832,000
Premises and equipment, net			(2,919,000)
Deferred tax asset, net			813,000	193,000
Intangibles			1,370,000	1,127,000
Other real estate owned			(100,000)	(1,862,000)
Interest Receivable			(280,000)
Prepaids			(174,000)
Goodwill			(231,000)
Total assets acquired			(2,177,000)	(542,000)
Liabilities:
Time deposit premium			729,000
Total liabilities assumed			729,000
Consideration transferred:
Aggregate fair value adjustments			(2,906,000)	(542,000)
Goodwill			$ 8,800,000	$ 8,844,000