Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Statement of Comprehensive Income [Abstract]
Net income	$ 5,264	$ 5,601	$ 15,156	$ 13,264
Securities available for sale:
Unrealized (losses) gains arising during the period	(218)	197	(1,325)	884
Reclassification of net (gains) losses included in net income (net of tax (benefit) expense) of $0 and ($1) for the third quarter of 2018 and 2017, respectively, and $0 and $5 for the nine months ended September 30, 2018 and 2017, respectively	0	2	0	(6)
Derivatives and hedging activities:
Unrealized gains arising during the period	234	127	855	127
Income tax benefit (expense) related to unrealized gains and losses	44	(80)	290	(334)
Other comprehensive income (loss), net of tax	60	246	(180)	671
Comprehensive income	5,324	5,847	14,976	13,935
Less: comprehensive income attributable to the noncontrolling interest	0	78	0	327
Comprehensive income attributable to Northrim BanCorp, Inc.	$ 5,324	$ 5,769	$ 14,976	$ 13,608