Regulatory Matters (Details) (USD $)	3 Months Ended
	Dec. 31, 2005	Jun. 30, 2003	Dec. 31, 2012 Northrim Bancorp, Inc. [Member]	Dec. 31, 2011 Northrim Bancorp, Inc. [Member]	Dec. 31, 2012 Northrim Bank [Member]	Dec. 31, 2011 Northrim Bank [Member]
Trust preferred securities offerings completed	$ 18,000,000	$ 18,000,000
Total Capital (to risk-weighted assets), Actual Amount			158,820,000	147,848,000	143,684,000	135,394,000
Total Capital (to risk-weighted assets), Actual Ratio			16.60%	16.46%	15.12%	15.14%
Total Capital (to risk-weighted assets), Adequately-Capitalized Amount			76,540,000	71,858,000	76,023,000	71,542,000
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			95,675,000	89,823,000	95,029,000	89,428,000
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			146,802,000	136,553,000	131,748,000	124,152,000
Tier 1 Capital (to risk-weighted assets), Actual Ratio			15.34%	15.20%	13.87%	13.89%
Tier 1 Capital (to risk-weighted assets), Adequately-Capitalized Amount			38,280,000	35,935,000	37,995,000	35,753,000
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			57,419,000	53,903,000	56,993,000	53,629,000
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			146,802,000	136,553,000	131,748,000	124,152,000
Tier I Capital (to average assets), Actual Ratio			12.99%	12.83%	11.74%	11.72%
Tier I Capital (to average assets), Adequately-Capitalized Amount			45,205,000	42,573,000	44,889,000	42,373,000
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			$ 56,506,000	$ 53,216,000	$ 56,111,000	$ 52,966,000
Tier I Capital (to average assets), Well-Capitalized Ratio			5.00%	5.00%	5.00%	5.00%