Parent Company Information - Statements Of Cash Flows (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Operating Activities:
Net income	$ 37,517	$ 32,888	$ 20,691
Adjustments to Reconcile Net Income to Net Cash Provided by Operating Activities:
Gain on sale of securities, net	(67)	(98)	(23)
Unrealized loss (gain) on marketable equity securities	101	(61)	(911)
Stock-based compensation	1,073	943	832
Net Cash Provided (Used) by Operating Activities	111,989	(36,454)	(821)
Investing Activities:
Purchases of marketable equity securities	(493)	(1,552)	0
Proceeds from sales/calls/maturities of marketable equity securities	1,084	601	229
Net Cash (Used) Provided by Investing Activities	(159,089)	(382,825)	(71,920)
Financing Activities:
Dividends paid to shareholders	(9,388)	(8,844)	(8,512)
Proceeds from the issuance of common stock	1,543	84	73
Repurchase of common stock	(11,534)	(9,976)	(12,569)
Net Cash Provided by Financing Activities	576,962	439,820	90,627
Net Change in Cash and Cash Equivalents	529,862	20,541	17,886
Cash and Cash Equivalents at Beginning of Year	115,965	95,424	77,538
Cash and Cash Equivalents at End of Year	645,827	115,965	95,424
Northrim Bancorp, Inc.
Operating Activities:
Net income	37,517	32,888	20,691
Adjustments to Reconcile Net Income to Net Cash Provided by Operating Activities:
Gain on sale of securities, net	(67)	(98)	0
Equity in undistributed earnings from subsidiaries	(38,691)	(33,744)	(20,897)
Unrealized loss (gain) on marketable equity securities	101	(61)	(911)
Stock-based compensation	1,073	943	832
Changes in other assets and liabilities	(2,167)	(2,118)	8,556
Net Cash Provided (Used) by Operating Activities	(2,234)	(2,190)	8,271
Investing Activities:
Purchases of marketable equity securities	(493)	(1,552)	0
Proceeds from sales/calls/maturities of marketable equity securities	1,016	503	229
Investment in Northrim Bank, NISC & NST2	31,894	21,423	19,488
Net Cash (Used) Provided by Investing Activities	32,417	20,374	19,717
Financing Activities:
Dividends paid to shareholders	(9,388)	(8,844)	(8,512)
Proceeds from the issuance of common stock	1,543	84	73
Repurchase of common stock	(11,534)	(9,976)	(12,569)
Net Cash Provided by Financing Activities	(19,379)	(18,736)	(21,008)
Net Change in Cash and Cash Equivalents	10,804	(552)	6,980
Cash and Cash Equivalents at Beginning of Year	24,742	25,294	18,314
Cash and Cash Equivalents at End of Year	$ 35,546	$ 24,742	$ 25,294