Parent Company Information - Statements Of Cash Flows (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Operating Activities:
Net income	$ 25,394	$ 30,741	$ 37,517
Adjustments to Reconcile Net Income to Net Cash Provided by Operating Activities:
Gain on sale of securities, net	0	0	(67)
Unrealized (gain) loss on marketable equity securities	(120)	1,119	101
Stock-based compensation	937	742	1,073
Net Cash Provided by Operating Activities	38,925	78,123	111,989
Investing Activities:
Purchases of marketable equity securities	(2,297)	(3,934)	(493)
Proceeds from sales/calls/maturities of marketable equity securities	0	488	1,084
Net Cash (Used) by Investing Activities	(255,071)	(405,625)	(159,089)
Financing Activities:
Dividends paid to shareholders	(13,609)	(10,571)	(9,388)
Proceeds from the issuance of common stock	555	586	1,543
Repurchase of common stock	(9,044)	(14,157)	(11,534)
Net Cash Provided (Used) by Financing Activities	75,326	(58,975)	576,962
Net Change in Cash and Cash Equivalents	(140,820)	(386,477)	529,862
Cash and Cash Equivalents at Beginning of Year	259,350	645,827	115,965
Cash and Cash Equivalents at End of Year	118,530	259,350	645,827
Northrim Bancorp, Inc.
Operating Activities:
Net income	25,394	30,741	37,517
Adjustments to Reconcile Net Income to Net Cash Provided by Operating Activities:
Gain on sale of securities, net	0	0	(67)
Equity in undistributed earnings from subsidiaries	(26,892)	(32,732)	(38,691)
Unrealized (gain) loss on marketable equity securities	(120)	1,119	101
Stock-based compensation	937	742	1,073
Changes in other assets and liabilities	(1,380)	(1,268)	(2,167)
Net Cash Provided by Operating Activities	(2,061)	(1,398)	(2,234)
Investing Activities:
Purchases of marketable equity securities	(2,297)	(3,934)	(493)
Proceeds from sales/calls/maturities of marketable equity securities	0	488	1,016
Investment in Northrim Bank, NISC & NST2	14,628	24,323	31,894
Net Cash (Used) by Investing Activities	12,331	20,877	32,417
Financing Activities:
Dividends paid to shareholders	(13,609)	(10,571)	(9,388)
Proceeds from the issuance of common stock	555	586	1,543
Repurchase of common stock	(9,044)	(14,157)	(11,534)
Net Cash Provided (Used) by Financing Activities	(22,098)	(24,142)	(19,379)
Net Change in Cash and Cash Equivalents	(11,828)	(4,663)	10,804
Cash and Cash Equivalents at Beginning of Year	30,883	35,546	24,742
Cash and Cash Equivalents at End of Year	$ 19,055	$ 30,883	$ 35,546