Subsequent Events	6 Months Ended
Jun. 30, 2026
Subsequent Events [Abstract]
Subsequent Events	SUBSEQUENT EVENTS The Company evaluated subsequent events through August 6, 2026, the date the consolidated financial statements were issued. On July 1, 2026, Arrow completed its acquisition of Adirondack Bancorp, Inc. (“Adirondack”), the parent company of Adirondack Bank, a New York-chartered community bank. At the effective time, Adirondack Bank merged into Arrow Bank. Arrow expects systems conversion and other integration activities to be completed later in 2026. As previously disclosed, Arrow and Adirondack entered into an Agreement and Plan of Merger dated February 25, 2026, and announced the transaction on February 26, 2026. The transaction closed on July 1, 2026. Under the terms of the merger agreement, Arrow acquired 100% of the outstanding voting equity interests of Adirondack. At the effective time of the merger, each share of Adirondack common stock outstanding was converted into the right to receive 1.8610 shares of Arrow common stock and $18.72 in cash. In connection with the merger, Arrow issued approximately 1.98 million shares of its common stock with an acquisition-date fair value of approximately $81 million and paid approximately $19.9 million in cash. The fair value of the common stock issued was determined using Arrow’s opening common-stock price of $41.06 per share on July, 1 2026. Preliminary aggregate consideration transferred was approximately $101 million, consisting of $81 million of common stock and $19.9 million of cash. The strategic acquisition expanded the Company's presence across the Upstate and Central New York area, with the addition of 20 branches. The acquisition of Adirondack Bank will be accounted for as a business combination in accordance with ASC 805, using the acquisition method of accounting. Due to the acquisition date being subsequent to June 30, 2026, the initial accounting for the business combination is in progress. Accordingly, the Company will include relevant disclosures as required by ASC 805 in the third quarter of 2026. Subsequent to July 1, 2026, Arrow sold approximately $74 million in low-yielding securities acquired from Adirondack Bank. Proceeds and cash on hand were used to pay down borrowings of $125 million. The Company terminated interest rate swap agreements with an aggregate notional amount of $125 million and received a net settlement amount of $1.2 million in connection with the termination.

The Company evaluated subsequent events through August 6, 2026, the date the consolidated financial statements were issued. On July 1, 2026, Arrow completed its acquisition of Adirondack Bancorp, Inc. (“Adirondack”), the parent company of Adirondack Bank, a New York-chartered community bank. At the effective time, Adirondack Bank merged into Arrow Bank. Arrow expects systems conversion and other integration activities to be completed later in 2026.

As previously disclosed, Arrow and Adirondack entered into an Agreement and Plan of Merger dated February 25, 2026, and announced the transaction on February 26, 2026. The transaction closed on July 1, 2026. Under the terms of the merger agreement, Arrow acquired 100% of the outstanding voting equity interests of Adirondack. At the effective time of the merger, each share of Adirondack common stock outstanding was converted into the right to receive 1.8610 shares of Arrow common stock and $18.72 in cash. In connection with the merger, Arrow issued approximately 1.98 million shares of its common stock with an acquisition-date fair value of approximately $81 million and paid approximately $19.9 million in cash. The fair value of the common stock issued was determined using Arrow’s opening common-stock price of $41.06 per share on July, 1 2026. Preliminary aggregate consideration transferred was approximately $101 million, consisting of $81 million of common stock and $19.9 million of cash.

The acquisition of Adirondack Bank will be accounted for as a business combination in accordance with ASC 805, using the acquisition method of accounting. Due to the acquisition date being subsequent to June 30, 2026, the initial accounting for the business combination is in progress. Accordingly, the Company will include relevant disclosures as required by ASC 805 in the third quarter of 2026.

Subsequent to July 1, 2026, Arrow sold approximately $74 million in low-yielding securities acquired from Adirondack Bank. Proceeds and cash on hand were used to pay down borrowings of $125 million. The Company terminated interest rate swap agreements with an aggregate notional amount of $125 million and received a net settlement amount of $1.2 million in connection with the termination.