Consolidated Statements of Changes In Shareholders' Equity (Unaudited) - 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, 2015		6,877,000
Beginning 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	(5,420)			(5,420)
Stock-based compensation expense	778		778
Exercise of stock options and vesting of restricted stock units, net (in shares)		21,000
Exercise of stock options and vesting of restricted stock units, net	(162)	$ 21	(183)
Write-off of deferred tax assets in excess of tax benefits from share-based payment arrangements	(63)		(63)
Distributions to noncontrolling interest	(640)					(640)
Other comprehensive income, net of tax	15				15
Net income attributable to the noncontrolling interest	579					579
Net income attributable to Northrim BanCorp, Inc.	$ 14,411			14,411
Ending balance (in shares) at Dec. 31, 2016	6,897,890	6,898,000
Ending 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	(1,457)			(1,457)
Stock-based compensation expense	128		128
Exercise of stock options and vesting of restricted stock units, net (in shares)		12,000
Exercise of stock options and vesting of restricted stock units, net	(132)	$ 12	(144)
Distributions to noncontrolling interest	(87)					(87)
Other comprehensive income, net of tax	366				366
Net income attributable to the noncontrolling interest	97					97
Net income attributable to Northrim BanCorp, Inc.	$ 3,825			3,825
Ending balance (in shares) at Mar. 31, 2017	6,909,865	6,910,000
Ending balance, value at Mar. 31, 2017	$ 189,452	$ 6,910	$ 62,936	$ 119,509	$ (31)	$ 128