Parent Company Information - Statements Of Cash Flows (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Operating Activities:
Net income attributable to Northrim BanCorp, Inc.	$ 4,106	$ 5,335	$ 4,781	$ 3,561	$ 6,674	$ 3,707	$ 4,369	$ 2,658	$ 17,783	$ 17,408	$ 12,325
Adjustments to Reconcile Net Income to Net Cash Provided by Operating Activities:
Stock-based compensation									608	360	506
Net Cash Provided by Operating Activities									10,519	20,478	18,648
Investing Activities:
Purchases of investment securities available for sale									(210,308)	(264,943)	(140,856)
Net cash received from Alaska Pacific acquisition									0	6,367	0
Net Cash Used by Investing Activities									(63,339)	(48,658)	(107,989)
Financing Activities:
Dividends paid to shareholders									(5,117)	(4,750)	(4,215)
Net Cash Provided by Financing Activities									42,937	11,145	33,619
Net Decrease in Cash and Cash Equivalents									(9,883)	(17,035)	(55,722)
Cash and Cash Equivalents at Beginning of Year				68,556				85,591	68,556	85,591	141,313
Cash and Cash Equivalents at End of Year	58,673				68,556				58,673	68,556	85,591
Northrim Bancorp, Inc.
Operating Activities:
Net income attributable to Northrim BanCorp, Inc.									17,783	17,408	12,325
Adjustments to Reconcile Net Income to Net Cash Provided by Operating Activities:
Equity in undistributed earnings from subsidiaries									(19,005)	(19,525)	(13,683)
Stock-based compensation									608	360	506
Changes in other assets and liabilities									(298)	(241)	(60)
Net Cash Provided by Operating Activities									(912)	(1,998)	(912)
Investing Activities:
Purchases of investment securities available for sale									(3,549)	0	525
Proceeds from sales/calls/maturities of securities available for sale									2,998	0	0
Net cash received from Alaska Pacific acquisition									0	6,367	0
Investment in Northrim Bank, NISC, NCT1 & NST2									9,842	(3,000)	5,874
Net Cash Used by Investing Activities									9,291	3,367	6,399
Financing Activities:
Dividends paid to shareholders									(5,117)	(4,750)	(4,215)
Proceeds from issuance of common stock and excess tax benefits									106	150	100
Net Cash Provided by Financing Activities									(5,011)	(4,600)	(4,115)
Net Decrease in Cash and Cash Equivalents									3,368	(3,231)	1,372
Cash and Cash Equivalents at Beginning of Year				$ 6,890				$ 10,121	6,890	10,121	8,749
Cash and Cash Equivalents at End of Year	$ 10,258				$ 6,890				$ 10,258	$ 6,890	$ 10,121