Regulatory Capital (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Total capital (to risk-weighted assets)
Actual, Amount	$ 1,005,980	$ 923,574
Actual, Ratio	18.97%	20.09%
Minimum capital requirement, Amount	424,322	367,701
Minimum capital requirement, Ratio	8.00%	8.00%
Well capitalized requirement, Amount	530,402	459,627
Well capitalized requirement, Ratio	10.00%	10.00%
Tier 1 capital (to risk-weighted assets)
Actual, Amount	938,887	865,213
Actual, Ratio	17.70%	18.82%
Minimum capital requirement, Amount	212,161	183,851
Minimum capital requirement, Ratio	4.00%	4.00%
Well capitalized requirement, Amount	318,241	275,776
Well capitalized requirement, Ratio	6.00%	6.00%
Tier 1 capital (to average assets)
Actual, Amount	938,887	865,213
Actual, Ratio	12.11%	11.31%
Minimum capital requirement, Amount	310,082	306,005
Minimum capital requirement, Ratio	4.00%	4.00%
Glacier Bank
Total capital (to risk-weighted assets)
Actual, Amount	948,618	851,819
Actual, Ratio	17.93%	18.79%
Minimum capital requirement, Amount	423,235	362,711
Minimum capital requirement, Ratio	8.00%	8.00%
Well capitalized requirement, Amount	529,044	453,388
Well capitalized requirement, Ratio	10.00%	10.00%
Tier 1 capital (to risk-weighted assets)
Actual, Amount	881,692	794,228
Actual, Ratio	16.67%	17.52%
Minimum capital requirement, Amount	211,618	181,355
Minimum capital requirement, Ratio	4.00%	4.00%
Well capitalized requirement, Amount	317,426	272,033
Well capitalized requirement, Ratio	6.00%	6.00%
Tier 1 capital (to average assets)
Actual, Amount	881,692	794,228
Actual, Ratio	11.44%	10.55%
Minimum capital requirement, Amount	308,281	301,013
Minimum capital requirement, Ratio	4.00%	4.00%
Well capitalized requirement, Amount	$ 385,351	$ 376,267
Well capitalized requirement, Ratio	5.00%	5.00%