Consolidated Statement of Changes in Shareholders' Equity - USD ($) $ in Thousands	Common Stock	Additional Paid-In Capital	Unallocated Common Stock Held by ESOP	Retained Earnings Impact of Adoption	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Impact of Adoption	Total
Balance at the beginning (ASU 2016-13) at Dec. 31, 2022				$ (2,118)			$ (2,118)
Balance at the beginning at Dec. 31, 2022					$ 358,466	$ (14,401)		$ 344,065
Consolidated Statement of Changes in Shareholders' Equity
Net income					9,825			9,825
Other comprehensive income, net of tax						2,504		2,504
Proceeds of stock offering and issuance of common shares (net of costs of $9,600)	$ 410	$ 399,965						400,375
Proceeds of stock offering and issuance of common shares (net of costs of $9,600) (in shares)	40,997,500
Issuance of common shares donated to Needham Bank Charitable Foundation	$ 17	17,065						17,082
Issuance of common shares donated to Needham Bank Charitable Foundation (in shares)	1,708,229
Purchase of common shares held by the ESOP			$ (13,774)					(13,774)
Balance at the end (ASU 2023-02) at Dec. 31, 2023				$ (7,849)			$ (7,849)
Balance at the end at Dec. 31, 2023	$ 427	417,030	(13,774)		366,173	(11,897)		757,959
Balance at the end (in shares) at Dec. 31, 2023	42,705,729
Consolidated Statement of Changes in Shareholders' Equity
Net income					42,149			42,149
Other comprehensive income, net of tax						3,730		3,730
Net costs from stock offering and issuance of common shares		(225)						(225)
Purchase of common shares held by the ESOP			(33,397)					(33,397)
ESOP shares committed to be released		442	2,358					2,800
Balance at the end at Dec. 31, 2024	$ 427	417,247	(44,813)		400,473	(8,167)		765,167
Balance at the end (in shares) at Dec. 31, 2024	42,705,729
Consolidated Statement of Changes in Shareholders' Equity
Net income					50,302			50,302
Other comprehensive income, net of tax						5,031		5,031
Repurchase of common shares under share repurchase plans	$ (41)	(77,084)						(77,125)
Repurchase of common shares under share repurchase plans (in shares)	(4,163,808)
Restricted stock award issued	$ 13	(13)
Restricted stock award issued (in shares)	1,284,525
Shares of common stock issued for Provident acquisition	$ 59	114,595						114,654
Shares of common stock issued for Provident acquisition (in shares)	5,943,682
Stock-based compensation		2,910						2,910
ESOP shares committed to be released		1,209	2,359					3,568
Dividends declared and paid					(5,575)			(5,575)
Balance at the end at Dec. 31, 2025	$ 458	$ 458,864	$ (42,454)		$ 445,200	$ (3,136)		$ 858,932
Balance at the end (in shares) at Dec. 31, 2025	45,770,128