Consolidated Statements of Cash Flows (Parenthetical) $ in Millions	6 Months Ended
Jun. 30, 2019 USD ($)
Statement of Cash Flows [Abstract]
Amortization of operating lease right-of-use assets	$ 16.3
Amortization of operating lease liability	$ 16.3

Amount of amortization expense attributable to right-of-use asset from operating lease right-of-use asset.

No definition available.

Name:	nycb_OperatingLeaseRightOfUseAssetAmortization
Namespace Prefix:	nycb_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration