Acquisition of UpState New York Bancorp, Inc. and USNY Bank (Narrative) (Details) - USD ($)		3 Months Ended	9 Months Ended
	Jul. 07, 2020	Sep. 30, 2020	Sep. 30, 2020	Jun. 30, 2020	Jan. 08, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Dec. 31, 2018
Business Acquisition [Line Items]
Total Assets		$ 1,842,107,000	$ 1,842,107,000			$ 1,230,610,000
Deposits		1,515,922,000	1,515,922,000			957,529,000
Stockholders’ equity		190,547,000	190,547,000	$ 142,664,000		137,428,000	$ 134,894,000	$ 131,483,000	$ 122,285,000
Loans acquired with credit deterioration		15,410,000	15,410,000
Goodwill resulting from merger		$ 30,213,000	$ 30,213,000			$ 11,331,000
UpState New York Bancorp, Inc. [Member]
Business Acquisition [Line Items]
Total Assets				463,800,000
Deposits				412,800,000
Stockholders’ equity	$ 44,803,000			$ 44,800,000
Conversion of shares					0.9390
Cash paid per share	$ 33.33	$ 0.67	$ 0.67		$ 33.33
Percent exchanged for stock					90.00%
Percent exchanged for cash					10.00%
Payments to Acquire Businesses, Gross		$ 8,845,198
Business Acquisition, Equity Interest Issued or Issuable, Number of Shares	1,865,738	1,865,738
Loans Acquired Without Evidence Of Deterioration, Unpaid Principal Balance	$ 400,127,000
Loans Acquired Without Evidence Of Deterioration, Fair Value	393,580,000
Loans acquired with credit deterioration	15,410,000
Non-accretable difference for credit impaired loans acquired	5,213,000
Goodwill and intangible assets		$ 19,291,000	$ 19,291,000
Goodwill resulting from merger	$ 18,882,000	18,882,000	18,882,000
Asset Impairment Charges			0
Core deposit intangible		409,000	409,000
Accumulated depreciation		$ 19,000	$ 19,000