XML 124 R110.htm IDEA: XBRL DOCUMENT
v3.3.1.900

Fair Value Measurements of Investments Held by Retirement Plan (Parenthetical) (Detail) - Common/Collective Trusts - Equity - Large-Cap Value | Dec. 31, 2015 Stock
--- | ---
Minimum |
Defined Benefit Plan Disclosure [Line Items] |
Number of stocks held | 60
Maximum |
Defined Benefit Plan Disclosure [Line Items] |
Number of stocks held | 70

X
- Definition Number of Stocks + References No definition available. + Details
Name: | nyb_NumberofStocks
Namespace Prefix: | nyb_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
Name: | us-gaap_DefinedBenefitPlanDisclosureLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=nyb_CommonCollectiveTrustsEquityMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_InvestmentSecondaryCategorizationAxis=nyb_LargeCapValueMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RangeAxis=us-gaap_MinimumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RangeAxis=us-gaap_MaximumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |