Regulatory Matters (Details) (USD $)	3 Months Ended
	Dec. 31, 2005	Jun. 30, 2003	Dec. 31, 2013 Northrim Bancorp, Inc.	Dec. 31, 2012 Northrim Bancorp, Inc.	Dec. 31, 2013 Northrim Bank	Dec. 31, 2012 Northrim Bank
Trust preferred securities offerings completed	$ 18,000,000	$ 18,000,000
Total Capital (to risk-weighted assets), Actual Amount			168,587,000	158,820,000	151,308,000	143,684,000
Total Capital (to risk-weighted assets), Actual Ratio			16.61%	16.60%	15.00%	15.12%
Total Capital (to risk-weighted assets), Adequately-Capitalized Amount			81,198,000	76,540,000	80,698,000	76,023,000
Total Capital (to risk-weighted assets), Adequately-Capitalized Ratio			8.00%	8.00%	8.00%	8.00%
Total Capital (to risk-weighted assets), Well-Capitalized Amount			101,497,000	95,675,000	100,872,000	95,029,000
Total Capital (to risk-weighted assets), Well-Capitalized Ratio			10.00%	10.00%	10.00%	10.00%
Tier 1 Capital (to risk-weighted assets), Actual Amount			155,851,000	146,802,000	138,650,000	131,748,000
Tier 1 Capital (to risk-weighted assets), Actual Ratio			15.35%	15.34%	13.75%	13.87%
Tier 1 Capital (to risk-weighted assets), Adequately-Capitalized Amount			40,613,000	38,280,000	40,335,000	37,995,000
Tier 1 Capital (to risk-weighted assets), Adequately Capitalized Ratio			4.00%	4.00%	4.00%	4.00%
Tier 1 Capital (to risk-weighted assets), Well-Capitalized Amount			60,919,000	57,419,000	60,502,000	56,993,000
Tier 1 Capital (to risk-weighted assets), Well-Capitalized Ratio			6.00%	6.00%	6.00%	6.00%
Tier I Capital (to average assets), Actual Amount			155,851,000	146,802,000	138,650,000	131,748,000
Tier I Capital (to average assets), Actual Ratio			13.06%	12.99%	11.68%	11.74%
Tier I Capital (to average assets), Adequately-Capitalized Amount			47,734,000	45,205,000	47,483,000	44,889,000
Tier I Capital (to average assets), Adequately-Capitalized Ratio			4.00%	4.00%	4.00%	4.00%
Tier I Capital (to average assets), Well-Capitalized Amount			$ 59,667,000	$ 56,506,000	$ 59,354,000	$ 56,111,000
Tier I Capital (to average assets), Well-Capitalized Ratio			5.00%	5.00%	5.00%	5.00%