Goodwill and other intangibles (Details) - USD ($)	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020	Dec. 31, 2019
Finite-Lived Intangible Assets [Line Items]
Goodwill	$ 159,595,000	$ 159,595,000	$ 159,595,000	$ 159,595,000
Other Intangible Assets, Net	8,781,000	10,917,000	9,260,000	11,523,000
Amortization of Intangible Assets	479,000	606,000
Finite-lived Intangible Assets Acquired	14,456,000		14,456,000
Indefinite-lived Intangible Assets Acquired	1,300,000		1,300,000
Finite-Lived Intangible Assets, Accumulated Amortization	6,975,000		6,496,000
Finite-Lived Intangible Assets, Amortization Expense, Next Twelve Months	1,319,000
Finite-Lived Intangible Assets, Amortization Expense, Year Two	1,487,000
Finite-Lived Intangible Assets, Amortization Expense, Year Three	1,323,000
Finite-Lived Intangible Assets, Amortization Expense, Year Four	1,215,000
Finite-Lived Intangible Assets, Amortization Expense, Year Five	1,042,000
Intangible Assets, Gross (Excluding Goodwill)	15,756,000		15,756,000
Intangible Assets, Net (Including Goodwill)	168,376,000	$ 170,512,000	168,855,000	$ 171,118,000
Core Deposits [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Accumulated Amortization	5,675,000		5,196,000
Trade Names [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Accumulated Amortization	$ 1,300,000		$ 1,300,000