XML 15 R54.htm IDEA: XBRL DOCUMENT
v2.4.0.8

Nature of Operations and Summary of Significant Accounting Policies (Details Textual) | 12 Months Ended
--- | ---
Dec. 31, 2013
Nature of Operations and Summary of Significant Accounting Policies |
Number of Bank Divisions | 13
Number of Operating Segments | 1
Maximum Period of Original Maturity to be Included in Cash and Cash Equivalents | 3 months
Minimum period past due to consider loan as delinquent | 30 days
Minimum period past due to consider loan as non accrual | 90 days
Minimum number of days delinquent to charge off consumer loans | 120 days
Maximum period up to which purchase price of business is allocated to assets acquired and liabilities assumed | 1 year
Number of Reporting Units Subsequent to Aggregation for Goodwill Assessment | 1
Percentage of likelihood for term more likely than not | 50.00%
Minimum Range |
Nature of Operations and Summary of Significant Accounting Policies |
Number of years for home equity loan origination term | 10 years
Minimum Range | Office Buildings |
Nature of Operations and Summary of Significant Accounting Policies |
Useful life of premises and equipment | 15 years
Minimum Range | Furniture, fixtures and equipment |
Nature of Operations and Summary of Significant Accounting Policies |
Useful life of premises and equipment | 3 years
Maximum Range |
Nature of Operations and Summary of Significant Accounting Policies |
Number of years for home equity loan origination term | 15 years
Maximum Range | Office Buildings |
Nature of Operations and Summary of Significant Accounting Policies |
Useful life of premises and equipment | 40 years
Maximum Range | Furniture, fixtures and equipment |
Nature of Operations and Summary of Significant Accounting Policies |
Useful life of premises and equipment | 10 years

X
- Definition Maximum Period of Original Maturity to be Included in Cash and Cash Equivalents + References No definition available. + Details
Name: | gbci_MaximumPeriodofOriginalMaturitytobeIncludedinCashandCashEquivalents
Namespace Prefix: | gbci_
Data Type: | us-types:durationStringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Maximum Period up to Which Purchase Price of Business is Allocated to Assets Acquired and Liabilities Assumed. + References No definition available. + Details
Name: | gbci_MaximumPeriodUpToWhichPurchasePriceOfBusinessIsAllocatedToAssetsAcquiredAndLiabilitiesAssumed
Namespace Prefix: | gbci_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Minimum number of days delinquent to charge off consumer loans. + References No definition available. + Details
Name: | gbci_MinimumNumberofDaysDelinquenttoChargeoffConsumerLoans
Namespace Prefix: | gbci_
Data Type: | us-types:durationStringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Minimum period past due to consider loan as delinquent. + References No definition available. + Details
Name: | gbci_MinimumPeriodPastDuetoConsiderLoanasDelinquent
Namespace Prefix: | gbci_
Data Type: | us-types:durationStringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Minimum period past due to consider loan as non accrual. + References No definition available. + Details
Name: | gbci_MinimumPeriodPastDuetoConsiderLoanasNonAccrual
Namespace Prefix: | gbci_
Data Type: | us-types:durationStringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | gbci_NatureOfOperationsAndSummaryOfSignificantAccountingPoliciesTextualAbstract
Namespace Prefix: | gbci_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Number of Bank Divisions + References No definition available. + Details
Name: | gbci_NumberOfBankDivisions
Namespace Prefix: | gbci_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition Number of Reporting Units Subsequent to Aggregation for Goodwill Assessment + References No definition available. + Details
Name: | gbci_NumberOfReportingUnitsSubsequentToAggregationForGoodwillAssessment
Namespace Prefix: | gbci_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition Number of years for home equity loan origination term + References No definition available. + Details
Name: | gbci_Numberofyearsforhomeequityloanoriginationterm
Namespace Prefix: | gbci_
Data Type: | us-types:durationStringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Percentage of likelihood for term more likely than not. + References No definition available. + Details
Name: | gbci_PercentageOfLikelihoodForTermMoreLikelyThanNot
Namespace Prefix: | gbci_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Number of operating segments. An operating segment is a component of an enterprise: (a) that engages in business activities from which it may earn revenues and incur expenses (including revenues and expenses relating to transactions with other components of the same enterprise), (b) whose operating results are regularly reviewed by the enterprise's chief operating decision maker to make decisions about resources to be allocated to the segment and assess its performance, and (c) for which discrete financial information is available. An operating segment may engage in business activities for which it has yet to earn revenues, for example, start-up operations may be operating segments before earning revenues. + References No definition available. + Details
Name: | us-gaap_NumberOfOperatingSegments
Namespace Prefix: | us-gaap_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Useful life of long lived, physical assets used in the normal conduct of business and not intended for resale, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Examples include, but not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment. + References No definition available. + Details
Name: | us-gaap_PropertyPlantAndEquipmentUsefulLife
Namespace Prefix: | us-gaap_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration