Business Combination - Consideration paid and estimated fair value of the acquired assets and liabilities (Details) - USD ($) $ in Thousands			3 Months Ended								12 Months Ended
	Oct. 31, 2020	Oct. 30, 2020	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Consideration Paid :
Cash payment											$ 54,836	$ 0	$ 0
Liabilities assumed:
Goodwill			$ 17,636				$ 16,127				17,636	16,127
Provision for credit loan losses			$ 3,862	$ 2,470	$ 9,619	$ 7,178	$ (318)	$ 683	$ 1,474	$ 972	$ 22,600	$ 2,811	$ 575
Empire
Consideration Paid :
Company stock issued ( 2,557,028 shares )		$ 32,705
Shares		2,557,028
Cash payment		$ 54,836
Total consideration paid		87,541
Assets acquired:
Cash and Cash Equivalents		86,340
Securities available for sale		159,369
Net loans		669,682
Interest and dividends receivable		5,394
Bank premises and equipment, net		3,203
Federal Home Loan Bank of New York stock, at cost		1,135
Bank owned life insurance		21,992
Core deposit Intangibles		3,280
Right of Use Asset		9,993
Other assets		22,300
Total		982,688
Liabilities assumed:
Non-interest bearing		169,496
Interest-bearing		685,393
Mortgagors' escrow deposits		6,406
Borrowed funds		21,215
Operating lease liability		11,039
Other liabilities		3,108
Total		896,657
Goodwill		1,509
Noncredit Discount	$ 7,600	$ 7,616
Provision for credit loan losses	$ 4,100