Junior Subordinated Debentures (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended							12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2013 Northrim Capital Trust 1	Dec. 31, 2012 Northrim Capital Trust 1	Dec. 31, 2011 Northrim Capital Trust 1	May 31, 2003 Northrim Capital Trust 1	Dec. 31, 2013 Northrim Capital Trust 2	Dec. 31, 2012 Northrim Capital Trust 2	Dec. 31, 2011 Northrim Capital Trust 2	Dec. 31, 2005 Northrim Capital Trust 2
Investment in unconsolidated trust	$ 40,666				$ 34,889				$ 40,666	$ 34,889					$ 8,000				$ 10,000
Junior subordinated debentures	18,558				18,558				18,558	18,558		8,200				10,300
LIBOR period												90 days				90 days
Basis plus 90-day LIBOR												3.15%				1.37%
Liquidation preference per capital security												$ 1,000				$ 1,000
Interest rate												3.39%				1.61%
Interest expense on deposits, borrowings and junior subordinated debentures	$ 497	$ 502	$ 511	$ 530	$ 569	$ 611	$ 627	$ 698	$ 2,040	$ 2,505	$ 3,544	$ 278	$ 292	$ 281		$ 167	$ 186	$ 171
Debt maturity date									Apr. 01, 2014			May 15, 2033				Mar. 15, 2036
Date debentures are redeemable												May 15, 2008				Mar. 15, 2011