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, 2014		6,854,000
Beginning balance, value at Dec. 31, 2014	$ 164,441	$ 6,854	$ 61,729	$ 95,493	$ 247	$ 118
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cash dividend declared	(5,126)			(5,126)
Stock-based compensation expense	608		608
Exercise of stock options (in shares)		23,000
Exercise of stock options	50	$ 23	27
Excess tax benefits (expense) from stock based payment arrangements	56		56
Distributions to noncontrolling interest	(490)					(490)
Other comprehensive income (loss), net of tax	(659)				(659)
Net income attributable to the noncontrolling interest	551					551
Net income attributable to Northrim BanCorp, Inc.	$ 17,783			17,783
Ending balance (in shares) at Dec. 31, 2015	6,877,140	6,877,000
Ending balance, value at Dec. 31, 2015	$ 177,214	$ 6,877	62,420	108,150	(412)	179
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cash dividend declared	(4,031)			(4,031)
Stock-based compensation expense	$ 531		531
Exercise of stock options (in shares)	5,342	5,000
Exercise of stock options	$ (60)	$ 5	(65)
Excess tax benefits (expense) from stock based payment arrangements	(35)		(35)
Distributions to noncontrolling interest	(205)					(205)
Other comprehensive income (loss), net of tax	1,049				1,049
Net income attributable to the noncontrolling interest	474					474
Net income attributable to Northrim BanCorp, Inc.	$ 10,821			10,821
Ending balance (in shares) at Sep. 30, 2016	6,882,482	6,882,000
Ending balance, value at Sep. 30, 2016	$ 185,758	$ 6,882	$ 62,851	$ 114,940	$ 637	$ 448