Parent Company Information - Statements Of Cash Flows (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Condensed Cash Flow Statements, Captions [Line Items]
Net income	$ 17,408	$ 12,325	$ 12,946
Stock-based compensation	360	506	454
Net Cash Provided (Used) by Operating Activities	20,478	18,648	32,549
Investment in securities available for sale	(264,943)	(140,856)	(111,431)
Alaska Pacific acquisition, net of cash received	6,367	0	0
Net Cash (Used) Provided by Investing Activities	(48,658)	(107,989)	(28,276)
Dividends paid to shareholders	(4,750)	(4,215)	(3,676)
Net Cash Provided by Financing Activities	11,145	33,619	57,510
Net Increase (Decrease) in Cash and Cash Equivalents	(17,035)	(55,722)	61,783
Cash and Cash Equivalents at Beginning of Year	85,591	141,313	79,530
Cash and Cash Equivalents at End of Year	68,556	85,591	141,313
Northrim Bancorp, Inc.
Condensed Cash Flow Statements, Captions [Line Items]
Net income	17,408	12,325	12,946
Equity in undistributed earnings from subsidiaries	(19,525)	(13,683)	(13,985)
Stock-based compensation	360	506	454
Changes in other assets and liabilities	241	60	(79)
Net Cash Provided (Used) by Operating Activities	(1,998)	(912)	(506)
Investment in securities available for sale	0	525	(2,527)
Alaska Pacific acquisition, net of cash received	6,367	0	0
Investment in Northrim Bank, NISC, NCT1 & NST2	(3,000)	5,874	7,921
Net Cash (Used) Provided by Investing Activities	3,367	6,399	5,394
Dividends paid to shareholders	(4,750)	(4,215)	(3,676)
Proceeds from issuance of common stock and excess tax benefits	150	100	233
Net Cash Provided by Financing Activities	(4,600)	(4,115)	(3,443)
Net Increase (Decrease) in Cash and Cash Equivalents	(3,231)	1,372	1,445
Cash and Cash Equivalents at Beginning of Year	10,121	8,749	7,304
Cash and Cash Equivalents at End of Year	$ 6,890	$ 10,121	$ 8,749