Consolidated Statements of Changes in Shareholders' Equity - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Non-controlling Interest
Beginning balance (in shares) at Dec. 31, 2016		6,898,000
Beginning balance, value at Dec. 31, 2016	$ 186,712	$ 6,898	$ 62,952	$ 117,141	$ (397)	$ 118
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cash dividend declared	(5,970)			(5,970)
Stock-based compensation expense	665		665
Exercise of stock options and vesting of restricted stock units, net (in shares)		32,000
Exercise of stock options and vesting of restricted stock units, net	$ (243)	$ 32	(275)
Repurchase of common stock (in shares)	(58,341)	(58,000)
Repurchase of common stock	$ (1,607)	$ (58)	1,549
Distributions to noncontrolling interest	(445)					(445)
Other comprehensive income (loss), net of tax	212				212
Reclassification for remeasuring of deferred tax asset related to investment securities	0			85	(85)
Net income attributable to the noncontrolling interest	327					327
Net income attributable to Northrim BanCorp, Inc.	13,151			13,151
Ending balance (in shares) at Dec. 31, 2017		6,872,000
Ending balance, value at Dec. 31, 2017	192,802	$ 6,872	61,793	124,407	(270)	0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cash dividend declared	(7,088)			(7,088)
Stock-based compensation expense	816		816
Exercise of stock options and vesting of restricted stock units, net (in shares)		27,000
Exercise of stock options and vesting of restricted stock units, net	$ 28	$ 27	1
Repurchase of common stock (in shares)	(15,468)	(16,000)
Repurchase of common stock	$ (494)	$ (16)	(478)
Other comprehensive income (loss), net of tax	(59)				(59)
Net income attributable to the noncontrolling interest	0
Net income attributable to Northrim BanCorp, Inc.	$ 20,004			20,004
Ending balance (in shares) at Dec. 31, 2018	6,883,216	6,883,000
Ending balance, value at Dec. 31, 2018	$ 205,947	$ 6,883	62,132	137,452	(520)	0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cash dividend declared	(8,528)			(8,528)
Stock-based compensation expense	832		832
Exercise of stock options and vesting of restricted stock units, net (in shares)		24,000
Exercise of stock options and vesting of restricted stock units, net	$ (207)	$ 24	(231)
Repurchase of common stock (in shares)	(347,676)	(348,000)
Repurchase of common stock	$ (12,569)	$ (348)	(12,221)
Other comprehensive income (loss), net of tax	951				951
Net income attributable to the noncontrolling interest	0
Net income attributable to Northrim BanCorp, Inc.	$ 20,691			20,691
Ending balance (in shares) at Dec. 31, 2019	6,558,809	6,559,000
Ending balance, value at Dec. 31, 2019	$ 207,117	$ 6,559	$ 50,512	$ 149,615	$ 431	$ 0