Borrowed Funds - Analysis of Contractual Maturities of Outstanding Repurchase Agreements Accounted for as Secured Borrowings (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Amount
Repurchase agreements	$ 800	$ 800
Contractual Maturity
Amount
2028	300
2029	500
Repurchase agreements	$ 800
Weighted Average Interest Rate
2028	2.37%
2029	2.16%
Contractual Maturity Over 90 days, Weighted Average Interest Rate	2.24%
Earlier of Contractual Maturity or Next Call Date
Amount
2022	$ 800
Repurchase agreements	$ 800
Weighted Average Interest Rate
2021	2.24%
Contractual Maturity Over 90 days, Weighted Average Interest Rate	2.24%

Securities Sold under Agreements to Repurchase, Maturities Summary [Abstract]

No definition available.

Name:	nycb_SecuritiesSoldUnderAgreementsToRepurchaseMaturitiesSummaryAbstract
Namespace Prefix:	nycb_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of cash received as security in return for loaning securities to another party which are due within one year of the Balance Sheet date.

+ References

No definition available.

+ Details

Name:	nycb_SecuritiesSoldUnderAgreementsToRepurchaseMaturitiesSummaryDueWithinOneYearOfBalanceSheetDate
Namespace Prefix:	nycb_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of cash received as security in return for loaning securities to another party which are due within three year of the Balance Sheet date.

+ References

No definition available.

+ Details

Name:	nycb_SecuritiesSoldUnderAgreementsToRepurchaseMaturitiesSummaryDueWithinThreeYearsOfBalanceSheetDate
Namespace Prefix:	nycb_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The weighted average interest rate applicable to the cash received as security in return for loaning securities to another party which are due from eight to nine years of the Balance Sheet date.

+ References

No definition available.

+ Details

Name:	nycb_SecuritiesSoldUnderAgreementsToRepurchaseMaturitiesSummaryWeightedAverageInterestRateEightToNineYearsFromBalanceSheetDate
Namespace Prefix:	nycb_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Securities Sold under Agreements to Repurchase, Maturities Summary, Weighted Average Interest Rate of Amounts Due [Abstract]

+ References

No definition available.

+ Details

Name:	nycb_SecuritiesSoldUnderAgreementsToRepurchaseMaturitiesSummaryWeightedAverageInterestRateOfAmountsDueAbstract
Namespace Prefix:	nycb_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The weighted average interest rate applicable to the cash received as security in return for loaning securities to another party which are due within one year of the Balance Sheet date.

+ References

No definition available.

+ Details

Name:	nycb_SecuritiesSoldUnderAgreementsToRepurchaseMaturitiesSummaryWeightedAverageInterestRateOfAmountsDueWithinOneYearOfBalanceSheetDate
Namespace Prefix:	nycb_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

The weighted average interest rate applicable to the cash received as security in return for loaning securities to another party which are due from twp to three years of the Balance Sheet date.

+ References

No definition available.

+ Details

Name:	nycb_SecuritiesSoldUnderAgreementsToRepurchaseMaturitiesSummaryWeightedAverageInterestRateTwoToThreeYearsFromBalanceSheetDate
Namespace Prefix:	nycb_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Securities Sold Under AgreementsTo Repurchase Maturities Summary Due With in Four Years Of Balance Sheet Date.

+ References

No definition available.

+ Details

Name:	nycb_SecuritiesSoldUnderAgreementstoRepurchaseMaturitiesSummaryDueWithInFourYearsOfBalanceSheetDate
Namespace Prefix:	nycb_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Interest rate on the amount to be repaid to the counterparty to the repurchase agreement when the carrying amount (or market value, if higher than the carrying amount) of securities or other assets sold under the repurchase agreement exceeds 10 percent of total assets.

+ References

+ Details

Name:	us-gaap_AssetsSoldUnderAgreementsToRepurchaseInterestRate
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount, after the effects of master netting arrangements, of funds outstanding borrowed in the form of a security repurchase agreement between the entity and another party for the sale and repurchase of identical or substantially the same securities at a date certain for a specified price. Includes liabilities not subject to a master netting arrangement and not elected to be offset.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(m)(1)(i))
-URI http://asc.fasb.org/extlink&oid=120395691&loc=d3e23780-122690

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 55
-Paragraph 10
-URI http://asc.fasb.org/extlink&oid=99393222&loc=SL20226008-175313

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(m)(1)(ii)(A)(i))
-URI http://asc.fasb.org/extlink&oid=120395691&loc=d3e23780-122690

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 50
-Paragraph 3
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=51824906&loc=SL20225862-175312

Reference 5: 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(1))
-URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878

+ Details

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

- Details

Name:	srt_FederalHomeLoanBankAdvancesBranchOfFHLBBankAxis=nycb_ContractualMaturityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_FederalHomeLoanBankAdvancesBranchOfFHLBBankAxis=nycb_EarlierOfContractualMaturityOrNextCallDateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: