Parent Company Information - Balance Sheets (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
ASSETS
Cash and cash equivalents	$ 50,551	$ 58,673	$ 68,556	$ 85,591
Investment securities available for sale	331,219	291,113
Other assets	56,128	51,774
Total assets	1,526,540	1,499,492	1,449,349
LIABILITIES
Junior subordinated debentures	18,558	18,558
Other liabilities	21,672	29,388
Total liabilities	1,339,828	1,322,278
SHAREHOLDERS' EQUITY
Common stock	6,898	6,877
Additional paid-in capital	62,952	62,420
Retained earnings	117,141	108,150
Accumulated other comprehensive loss	(397)	(412)
Total Northrim BanCorp, Inc. shareholders' equity	186,594	177,035
Total liabilities and shareholders' equity	1,526,540	1,499,492
Northrim Bancorp, Inc.
ASSETS
Cash and cash equivalents	11,963	10,258	$ 6,890	$ 10,121
Investment securities available for sale	4,967	3,524
Other assets	2,248	1,184
Total assets	205,734	195,903
LIABILITIES
Junior subordinated debentures	18,558	18,558
Other liabilities	582	310
Total liabilities	19,140	18,868
SHAREHOLDERS' EQUITY
Common stock	6,898	6,877
Additional paid-in capital	62,952	62,420
Retained earnings	117,141	108,150
Accumulated other comprehensive loss	(397)	(412)
Total Northrim BanCorp, Inc. shareholders' equity	186,594	177,035
Total liabilities and shareholders' equity	205,734	195,903
Northrim Bancorp, Inc. | Northrim Bank
ASSETS
Investment in subsidiary	184,511	178,905
Northrim Bancorp, Inc. | Northrim Investment Services Company
ASSETS
Investment in subsidiary	1,487	1,474
Northrim Bancorp, Inc. | Northrim Capital Trust 1
ASSETS
Investment in subsidiary	248	248
Northrim Bancorp, Inc. | Northrim Statutory Trust 2
ASSETS
Investment in subsidiary	$ 310	$ 310