Regulatory Capital (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Total capital (to risk-weighted assets)
Actual, Amount	$ 1,131,460	$ 1,065,282
Actual, Ratio	17.17%	18.93%
Minimum capital requirement, Amount	$ 527,160	$ 450,240
Minimum capital requirement, Ratio	8.00%	8.00%
Well capitalized requirement, Amount		$ 562,800
Well capitalized requirement, Ratio		10.00%
Tier 1 capital (to risk-weighted assets)
Actual, Amount	$ 1,048,505	$ 994,197
Actual, Ratio	15.91%	17.67%
Minimum capital requirement, Amount	$ 395,370	$ 225,120
Minimum capital requirement, Ratio	6.00%	4.00%
Well capitalized requirement, Amount		$ 337,680
Well capitalized requirement, Ratio		6.00%
Common Equity Tier 1 (to risk-weighted assets)
Actual, Amount	$ 926,523
Actual, Ratio	14.06%
Minimum capital requirement, Amount	$ 296,528
Minimum capital requirement, Ratio	4.50%
Tier 1 capital (to average assets)
Actual, Amount	$ 1,048,505	$ 994,197
Actual, Ratio	12.01%	12.45%
Minimum capital requirement, Amount	$ 349,066	$ 319,505
Minimum capital requirement, Ratio	4.00%	4.00%
Glacier Bank
Total capital (to risk-weighted assets)
Actual, Amount	$ 1,093,669	$ 1,023,669
Actual, Ratio	16.66%	18.25%
Minimum capital requirement, Amount	$ 525,228	$ 448,739
Minimum capital requirement, Ratio	8.00%	8.00%
Well capitalized requirement, Amount	$ 656,535	$ 560,924
Well capitalized requirement, Ratio	10.00%	10.00%
Tier 1 capital (to risk-weighted assets)
Actual, Amount	$ 1,010,981	$ 952,815
Actual, Ratio	15.40%	16.99%
Minimum capital requirement, Amount	$ 393,921	$ 224,370
Minimum capital requirement, Ratio	6.00%	4.00%
Well capitalized requirement, Amount	$ 525,228	$ 336,554
Well capitalized requirement, Ratio	8.00%	6.00%
Common Equity Tier 1 (to risk-weighted assets)
Actual, Amount	$ 1,010,981
Actual, Ratio	15.40%
Minimum capital requirement, Amount	$ 295,441
Minimum capital requirement, Ratio	4.50%
Well capitalized requirement, Amount	$ 426,748
Well capitalized requirement, Ratio	6.50%
Tier 1 capital (to average assets)
Actual, Amount	$ 1,010,981	$ 952,815
Actual, Ratio	11.66%	12.03%
Minimum capital requirement, Amount	$ 346,715	$ 316,938
Minimum capital requirement, Ratio	4.00%	4.00%
Well capitalized requirement, Amount	$ 433,394	$ 396,173
Well capitalized requirement, Ratio	5.00%	5.00%