Federal Home Loan Bank Membership (Narrative) (Details) - USD ($)	9 Months Ended
Sep. 30, 2020	Dec. 31, 2019
Federal Home Loan Bank Membership [Abstract]
Maximum percentage of admitted assets allowed for borrowing base	10.00%
Admitted assets for FHLBNY	$ 14,667,099,000
Maximum amount available under FHLBNY	1,466,709,000
Borrowings from FHLBNY	$ 90,000,000
FHLBNY interest rate	0.35%
FHLBNY amount of borrowed funds required to be used to acquire additional membership stock, percentage	4.50%
FHLBNY maturity date	Nov. 30, 2020

Amount of maximum advances or credit lines available from the Federal Home Loan Bank (FHLB).

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.13(3)(a))
-URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 470
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6479118&loc=d3e64650-112822

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22 (b))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

Name:	us-gaap_FederalHomeLoanBankAdvancesGeneralDebtObligationsDisclosuresMaximumAmountAvailable
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant