Business Combinations - Pro Forma Information (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		6 Months Ended			12 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014		Jun. 30, 2013	Dec. 31, 2013
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Pro Forma Revenue			$ 31,484		$ 28,332
Net Income Attributable to Northrim BanCorp	4,369	3,496	7,027		6,170	12,325
Earnings Per Share, Basic (USD per share)	$ 0.64	$ 0.54	$ 1.05		$ 0.95
Earnings per share, diluted (USD per share)	$ 0.63	$ 0.53	$ 1.04		$ 0.94
Weighted Average Shares Outstanding, Basic (shares)	6,829,897	6,515,414	6,683,897		6,513,935
Weighted Average Shares Outstanding, Diluted (shares)	6,919,568	6,591,003	6,774,434		6,590,899
Pro Forma Information, Revenue Since Acquisition			(4)		(20)
Pro Forma Information, Net Income (Loss) since Acquisition, Adjustment			(175)		113
Pro Forma Revenue			33,575		33,157
Pro Forma Net Income (Loss)			5,570		6,365
Pro Forma Earnings Per Share, Basic (USD per share)			$ 0.83		$ 0.98
Pro Forma Earnings Per Share, Diluted (USD per share)			$ 0.82		$ 0.97
Alaska Pacific Bank
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Pro Forma, Interest Income	2,400		2,095	[1]	4,845
Pro Forma Information, Net Income (Loss) Since Acquisition			$ (1,282)	[1]	$ 82

[1] Alaska Pacific represents results from January 1 to March 31 for 2014 and represents results from January 1 to June 30 for 2013.