Parent Company Information - Balance Sheets (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
ASSETS
Cash and cash equivalents	$ 58,673	$ 68,556	$ 85,591	$ 141,313
Investment securities available for sale	291,113	281,730
Other assets	51,774	57,762
Total assets	1,499,492	1,449,349
LIABILITIES
Junior subordinated debentures	18,558	18,558
Other liabilities	29,388	40,456
Total liabilities	1,322,278	1,284,908
SHAREHOLDERS' EQUITY
Common stock	6,877	6,854
Additional paid-in capital	62,420	61,729
Retained earnings	108,150	95,493
Accumulated other comprehensive income (loss)	(412)	247
Total Northrim BanCorp, Inc. shareholders' equity	177,035	164,323
Total liabilities and shareholders' equity	1,499,492	1,449,349
Northrim Bancorp, Inc.
ASSETS
Cash and cash equivalents	10,258	6,890	$ 10,121	$ 8,749
Investment securities available for sale	3,524	3,152
Due from NISC	0	101
Other assets	1,184	1,268
Total assets	195,903	183,192
LIABILITIES
Junior subordinated debentures	18,558	18,558
Other liabilities	310	311
Total liabilities	18,868	18,869
SHAREHOLDERS' EQUITY
Common stock	6,877	6,854
Additional paid-in capital	62,420	61,729
Retained earnings	108,150	95,493
Accumulated other comprehensive income (loss)	(412)	247
Total Northrim BanCorp, Inc. shareholders' equity	177,035	164,323
Total liabilities and shareholders' equity	195,903	183,192
Northrim Bank | Northrim Bancorp, Inc.
ASSETS
Investment in subsidiary	178,905	169,590
Northrim Investment Services Company | Northrim Bancorp, Inc.
ASSETS
Investment in subsidiary	1,474	1,633
Northrim Capital Trust 1 | Northrim Bancorp, Inc.
ASSETS
Investment in subsidiary	248	248
Northrim Statutory Trust 2 | Northrim Bancorp, Inc.
ASSETS
Investment in subsidiary	$ 310	$ 310