Summary Of Remaining Maturity Of The Undiscounted Lease Receivables (Detail) $ in Thousands	Mar. 31, 2020 USD ($)
Leases [Abstract]
2020	$ 38,441
2021	100,757
2022	284,259
2023	109,564
2024	114,568
Thereafter	943,124
Total lease payments	1,590,713
Plus: deferred origination costs	24,175
Less: unearned income	(106,450)
Total lease finance receivables, net	$ 1,508,438

Direct Financing Leases, Lease Receivable, Payments to be Received, Five Years.

No definition available.

Name:	nycb_DirectFinancingLeasesLeaseReceivablePaymentsToBeReceivedFiveYears
Namespace Prefix:	nycb_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Direct Financing Leases, Lease Receivable, Payments to be Received, Four Years.

+ References

No definition available.

+ Details

Name:	nycb_DirectFinancingLeasesLeaseReceivablePaymentsToBeReceivedFourYears
Namespace Prefix:	nycb_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Direct Financing Leases, Lease Receivable, Payments to be Received, Thereafter.

+ References

No definition available.

+ Details

Name:	nycb_DirectFinancingLeasesLeaseReceivablePaymentsToBeReceivedThereafter
Namespace Prefix:	nycb_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Direct Financing Leases, Lease Receivable, Payments to be Received, Three Years.

+ References

No definition available.

+ Details

Name:	nycb_DirectFinancingLeasesLeaseReceivablePaymentsToBeReceivedThreeYears
Namespace Prefix:	nycb_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Direct Financing Leases, Lease Receivable, Payments to be Received, Total.

+ References

No definition available.

+ Details

Name:	nycb_DirectFinancingLeasesLeaseReceivablePaymentsToBeReceivedTotal
Namespace Prefix:	nycb_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Direct Financing Leases, Lease Receivable, Payments to be Received, Two Years.

+ References

No definition available.

+ Details

Name:	nycb_DirectFinancingLeasesLeaseReceivablePaymentsToBeReceivedTwoYears
Namespace Prefix:	nycb_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Direct Financing Leases Lease Receivable Payments To Be Received Remainder Of Fiscal Year

+ References

No definition available.

+ Details

Name:	nycb_DirectFinancingLeasesLeaseReceivablePaymentstoBeReceivedRemainderOfFiscalYear
Namespace Prefix:	nycb_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Direct Financing Leases, Lease Receivable, Undiscounted Excess Amount

+ References

No definition available.

+ Details

Name:	nycb_DirectFinancingLeasesLeaseReceivableUndiscountedExcessAmount
Namespace Prefix:	nycb_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

This element represents costs incurred by the lessor that are (a) costs to originate a lease incurred in transactions with independent third parties that (i) result directly from and are essential to acquire that lease and (ii) would not have been incurred had that leasing transaction not occurred and (b) certain costs directly related to specified activities performed by the lessor for that lease. Those activities are: evaluating the prospective lessee's financial condition; evaluating and recording guarantees, collateral, and other security arrangements; negotiating lease terms; preparing and processing lease documents; and closing the transaction. This element is net of accumulated amortization.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 840
-SubTopic 20
-Section 25
-Paragraph 17
-URI http://asc.fasb.org/extlink&oid=77902619&loc=d3e40246-112709

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 840
-SubTopic 20
-Section 25
-Paragraph 16
-URI http://asc.fasb.org/extlink&oid=77902619&loc=d3e40588-112709

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 840
-SubTopic 20
-Section 35
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=77913719&loc=d3e40879-112712

+ Details

Name:	us-gaap_DeferredCostsLeasingNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Present value of lease payments not yet received by lessor and amount expected to be derived from underlying asset, following end of lease term, guaranteed by lessee or other third party unrelated to lessor, from direct financing lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 30
-Section 50
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=119202524&loc=SL77919379-209981

+ Details

Name:	us-gaap_DirectFinancingLeaseLeaseReceivable
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- References

No definition available.

+ Details

Name:	us-gaap_LeasesAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration