Subordinated Debentures (Details) (USD $) In Thousands, unless otherwise specified			12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2013 First Company Statutory Trust 2001	Dec. 31, 2013 First Company Statutory Trust 2003	Dec. 31, 2013 Glacier Capital Trust II	Dec. 31, 2013 Citizens (ID) Statutory Trust I	Dec. 31, 2013 Glacier Capital Trust III	Dec. 31, 2013 Glacier Capital Trust IV	Dec. 31, 2013 Bank of the San Juans Bancorporation Trust I
Terms of Subordinated Debentures
Balance	$ 125,562	$ 125,418	$ 3,018	$ 2,227	$ 46,393	$ 5,155	$ 36,083	$ 30,928	$ 1,758
Rate at December 31, 2013			3.537%	3.496%	2.994%	2.894%	1.533%	1.813%	2.058%
Variable Rate Structure			3 mo LIBOR plus 3.30	3 mo LIBOR plus 3.25	3 mo LIBOR plus 2.75	3 mo LIBOR plus 2.65	3 mo LIBOR plus 1.29	3 mo LIBOR plus 1.57	3 mo LIBOR plus 1.82
LIBOR Rate Spread			3.30%	3.25%	2.75%	2.65%	1.29%	1.57%	1.82%
Maturity Date			Jul. 31, 2031	Mar. 26, 2033	Apr. 07, 2034	Jun. 17, 2034	Apr. 07, 2036	Sep. 15, 2036	Mar. 01, 2037