Regulatory Capital (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Total capital (to risk-weighted assets)
Actual, Amount	$ 1,179,673	$ 1,131,460
Actual, Ratio	16.38%	17.17%
Minimum capital requirement, Amount	$ 576,092	$ 527,160
Minimum capital requirement, Ratio	8.00%	8.00%
Tier 1 capital (to risk-weighted assets)
Actual, Amount	$ 1,089,142	$ 1,048,505
Actual, Ratio	15.12%	15.91%
Minimum capital requirement, Amount	$ 432,069	$ 395,370
Minimum capital requirement, Ratio	6.00%	6.00%
Common Equity Tier 1 (to risk-weighted assets)
Actual, Amount	$ 966,701	$ 926,523
Actual, Ratio	13.42%	14.06%
Minimum capital requirement, Amount	$ 324,052	$ 296,528
Minimum capital requirement, Ratio	4.50%	4.50%
Tier 1 capital (to average assets)
Actual, Amount	$ 1,089,142	$ 1,048,505
Actual, Ratio	11.90%	12.01%
Minimum capital requirement, Amount	$ 365,994	$ 349,066
Minimum capital requirement, Ratio	4.00%	4.00%
Glacier Bank
Total capital (to risk-weighted assets)
Actual, Amount	$ 1,131,949	$ 1,093,669
Actual, Ratio	15.76%	16.66%
Minimum capital requirement, Amount	$ 574,658	$ 525,228
Minimum capital requirement, Ratio	8.00%	8.00%
Well capitalized requirement, Amount	$ 718,323	$ 656,535
Well capitalized requirement, Ratio	10.00%	10.00%
Tier 1 capital (to risk-weighted assets)
Actual, Amount	$ 1,041,640	$ 1,010,981
Actual, Ratio	14.50%	15.40%
Minimum capital requirement, Amount	$ 430,994	$ 393,921
Minimum capital requirement, Ratio	6.00%	6.00%
Well capitalized requirement, Amount	$ 574,658	$ 525,228
Well capitalized requirement, Ratio	8.00%	8.00%
Common Equity Tier 1 (to risk-weighted assets)
Actual, Amount	$ 1,041,640	$ 1,010,981
Actual, Ratio	14.50%	15.40%
Minimum capital requirement, Amount	$ 323,245	$ 295,441
Minimum capital requirement, Ratio	4.50%	4.50%
Well capitalized requirement, Amount	$ 466,910	$ 426,748
Well capitalized requirement, Ratio	6.50%	6.50%
Tier 1 capital (to average assets)
Actual, Amount	$ 1,041,640	$ 1,010,981
Actual, Ratio	11.45%	11.66%
Minimum capital requirement, Amount	$ 363,945	$ 346,715
Minimum capital requirement, Ratio	4.00%	4.00%
Well capitalized requirement, Amount	$ 454,932	$ 433,394
Well capitalized requirement, Ratio	5.00%	5.00%