Nature of Operations and Principles of Consolidation	3 Months Ended
Mar. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Nature of Operations and Principles of Consolidation	Note 1. Nature of Operations and Principles of Consolidation ConnectOne Bancorp, Inc. (the “Parent Corporation”) is incorporated under the laws of the State of New Jersey and is a registered bank holding company. The Parent Corporation’s business currently consists of the operation of its wholly-owned subsidiary, ConnectOne Bank (the “Bank” and, collectively with the Parent Corporation and the Parent Corporation’s subsidiaries, the “Company”). The Bank’s subsidiaries include Union Investment Co. (a New Jersey investment company), Twin Bridge Investment Co. (a Delaware investment company), ConnectOne Preferred Funding Corp. (a New Jersey real estate investment trust), Center Financial Group, LLC (a New Jersey financial services company), Center Advertising, Inc. (a New Jersey advertising company), Morris Property Company, LLC, (a New Jersey limited liability company), Volosin Holdings, LLC, (a New Jersey limited liability company), and NJCB Spec-1, LLC (a New Jersey limited liability company). The Bank is a community-based, full-service New Jersey-chartered commercial bank that was founded in 2005. The Bank operates from its headquarters located at 301 Sylvan Avenue in the Borough of Englewood Cliffs, Bergen County, New Jersey and through its twenty-one other banking offices. Substantially all loans are secured with various types of collateral, including business assets, consumer assets and commercial/residential real estate. Each borrower’s ability to repay its loans is dependent on the conversion of assets, cash flows generated from the borrowers’ business, real estate rental and consumer wages. The preceding unaudited consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States (“GAAP”) for interim financial information and with the instructions to Form 10-Q and Rule 10-01 of Regulation S-X, and, accordingly, do not include all of the information and footnotes required by GAAP for complete financial statements. However, in the opinion of management, all adjustments (consisting only of normal recurring accruals) considered necessary for a fair presentation have been included. Operating results for the three months ended March 31, 2018 are not necessarily indicative of the results that may be expected for the full year ending December 31, 2018, or for any other interim period. The Company’s 2017 Annual Report on Form 10-K should be read in conjunction with these consolidated financial statements. In preparing the consolidated financial statements, management has made estimates and assumptions that affect the reported amounts of assets and liabilities as of the dates of the consolidated statements of condition and that affect the results of operations for the periods presented. Actual results could differ significantly from those estimates. The consolidated financial statements have been prepared in conformity with GAAP. Some items in the prior year consolidated financial statements were reclassified to conform to current presentation. Reclassifications had no effect on prior year net income or stockholders’ equity.

Nature of Operations and Principles of Consolidation

3 Months Ended

Mar. 31, 2018

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Nature of Operations and Principles of Consolidation

Note 1. Nature of Operations and Principles of Consolidation

ConnectOne Bancorp, Inc. (the “Parent Corporation”) is incorporated under the laws of the State of New Jersey and is a registered bank holding company. The Parent Corporation’s business currently consists of the operation of its wholly-owned subsidiary, ConnectOne Bank (the “Bank” and, collectively with the Parent Corporation and the Parent Corporation’s subsidiaries, the “Company”). The Bank’s subsidiaries include Union Investment Co. (a New Jersey investment company), Twin Bridge Investment Co. (a Delaware investment company), ConnectOne Preferred Funding Corp. (a New Jersey real estate investment trust), Center Financial Group, LLC (a New Jersey financial services company), Center Advertising, Inc. (a New Jersey advertising company), Morris Property Company, LLC, (a New Jersey limited liability company), Volosin Holdings, LLC, (a New Jersey limited liability company), and NJCB Spec-1, LLC (a New Jersey limited liability company).

The Bank is a community-based, full-service New Jersey-chartered commercial bank that was founded in 2005. The Bank operates from its headquarters located at 301 Sylvan Avenue in the Borough of Englewood Cliffs, Bergen County, New Jersey and through its twenty-one other banking offices. Substantially all loans are secured with various types of collateral, including business assets, consumer assets and commercial/residential real estate. Each borrower’s ability to repay its loans is dependent on the conversion of assets, cash flows generated from the borrowers’ business, real estate rental and consumer wages.

The preceding unaudited consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States (“GAAP”) for interim financial information and with the instructions to Form 10-Q and Rule 10-01 of Regulation S-X, and, accordingly, do not include all of the information and footnotes required by GAAP for complete financial statements. However, in the opinion of management, all adjustments (consisting only of normal recurring accruals) considered necessary for a fair presentation have been included. Operating results for the three months ended March 31, 2018 are not necessarily indicative of the results that may be expected for the full year ending December 31, 2018, or for any other interim period. The Company’s 2017 Annual Report on Form 10-K should be read in conjunction with these consolidated financial statements.

In preparing the consolidated financial statements, management has made estimates and assumptions that affect the reported amounts of assets and liabilities as of the dates of the consolidated statements of condition and that affect the results of operations for the periods presented. Actual results could differ significantly from those estimates.

The consolidated financial statements have been prepared in conformity with GAAP. Some items in the prior year consolidated financial statements were reclassified to conform to current presentation. Reclassifications had no effect on prior year net income or stockholders’ equity.