Parent Company Information - Statements Of Cash Flows (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Operating Activities:
Net income	$ 36,971	$ 25,394	$ 30,741
Adjustments to Reconcile Net Income to Net Cash Provided by Operating Activities:
Gain on sale of securities, net	(112)	0	0
Unrealized (gain) loss on marketable equity securities	(465)	(120)	1,119
Stock-based compensation	913	937	742
Net Cash (Used) Provided by Operating Activities	(8,727)	38,775	78,072
Investing Activities:
Purchases of marketable equity securities	(1,964)	(2,297)	(3,934)
Proceeds from sales/calls/maturities of marketable equity securities	6,973	0	488
Net Cash (Used) by Investing Activities	(197,625)	(254,921)	(405,574)
Financing Activities:
Dividends paid to shareholders	(13,751)	(13,609)	(10,571)
Proceeds from the issuance of common stock	801	555	586
Repurchase of common stock	(789)	(9,044)	(14,157)
Net Cash Provided (Used) by Financing Activities	150,558	75,326	(58,975)
Net Change in Cash and Cash Equivalents	(55,794)	(140,820)	(386,477)
Cash and Cash Equivalents at Beginning of Year	118,530	259,350	645,827
Cash and Cash Equivalents at End of Year	62,736	118,530	259,350
Northrim Bancorp, Inc.
Operating Activities:
Net income	36,971	25,394	30,741
Adjustments to Reconcile Net Income to Net Cash Provided by Operating Activities:
Gain on sale of securities, net	112	0	0
Equity in undistributed earnings from subsidiaries	(37,252)	(26,892)	(32,732)
Unrealized (gain) loss on marketable equity securities	(465)	(120)	1,119
Stock-based compensation	913	937	742
Changes in other assets and liabilities	(60)	(1,380)	(1,268)
Net Cash (Used) Provided by Operating Activities	219	(2,061)	(1,398)
Investing Activities:
Purchases of marketable equity securities	(1,964)	(2,297)	(3,934)
Proceeds from sales/calls/maturities of marketable equity securities	6,973	0	488
Investment in Northrim Bank, NISC & NST2	(6,157)	14,628	24,323
Net Cash (Used) by Investing Activities	(1,148)	12,331	20,877
Financing Activities:
Dividends paid to shareholders	(13,751)	(13,609)	(10,571)
Proceeds from the issuance of common stock	801	555	586
Repurchase of common stock	(789)	(9,044)	(14,157)
Net Cash Provided (Used) by Financing Activities	(13,739)	(22,098)	(24,142)
Net Change in Cash and Cash Equivalents	(14,668)	(11,828)	(4,663)
Cash and Cash Equivalents at Beginning of Year	19,055	30,883	35,546
Cash and Cash Equivalents at End of Year	$ 4,387	$ 19,055	$ 30,883