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v2.4.1.9

Federal and State Income Taxes (Details Textual) (USD $) | 12 Months Ended |
--- | --- | ---
Dec. 31, 2014 | Dec. 31, 2013
Summary of Tax Credit Carryforwards |  |
Federal income tax credit carryforwards, Amount | $ 845,000us-gaap_TaxCreditCarryforwardAmount |
Federal Income Tax Credit Carryforwards, Expiration Date | Dec. 31, 2034 |
Income Tax Uncertainties |  |
Unrecognized income tax benefit | 0us-gaap_UnrecognizedTaxBenefits | 0us-gaap_UnrecognizedTaxBenefits
Accrued liabilities for the payment of interest or penalties | 0us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestAccrued | 0us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestAccrued
Valuation Allowance |  |
Deferred tax valuation allowance | 0us-gaap_DeferredTaxAssetsValuationAllowance | 0us-gaap_DeferredTaxAssetsValuationAllowance
Federal and State Income Taxes |  |
Base year reserve for bad debts | 3,600,000gbci_BadDebtReserveForTaxPurposesOfSavingsAndLoanAssociationsOrOtherQualifiedThriftLender |
Federal |  |
Operating Loss Carryforwards |  |
Operating Loss Carryforwards, Amount | 9,388,000us-gaap_OperatingLossCarryforwards / us-gaap_IncomeTaxAuthorityAxis = us-gaap_InternalRevenueServiceIRSMember |
Federal | Earliest Tax Year |  |
Operating Loss Carryforwards |  |
Operating Loss Carryforwards, Expiration Date | Dec. 31, 2029 |
Federal | Latest Tax Year |  |
Operating Loss Carryforwards |  |
Operating Loss Carryforwards, Expiration Date | Dec. 31, 2031 |
Colorado |  |
Operating Loss Carryforwards |  |
Operating Loss Carryforwards, Amount | $ 17,317,000us-gaap_OperatingLossCarryforwards / us-gaap_IncomeTaxAuthorityAxis = gbci_ColoradoMember |
Colorado | Earliest Tax Year |  |
Operating Loss Carryforwards |  |
Operating Loss Carryforwards, Expiration Date | Dec. 31, 2029 |
Colorado | Latest Tax Year |  |
Operating Loss Carryforwards |  |
Operating Loss Carryforwards, Expiration Date | Dec. 31, 2031 |

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- Definition Bad debt reserve for tax purposes of savings and loan associations or other qualified thrift lender. + References No definition available. + Details
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- Definition Amount of deferred tax assets for which it is more likely than not that a tax benefit will not be realized. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=6907707&loc=d3e32537-109319 + Details
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- Definition Amount of operating loss carryforward, before tax effects, available to reduce future taxable income under enacted tax laws. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 3 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=6907707&loc=d3e32559-109319 + Details
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- Definition Expiration date of each operating loss carryforward included in operating loss carryforward, in CCYY-MM-DD format. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 3 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=6907707&loc=d3e32559-109319 + Details
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- Definition The amount of the tax credit carryforward, before tax effects, available to reduce future taxable income under enacted tax laws. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 3 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=6907707&loc=d3e32559-109319 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Carryforwards -URI http://asc.fasb.org/extlink&oid=6506874 + Details
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- Definition Expiration date of the tax credit carryforward, in CCYY-MM-DD format. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 3 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=6907707&loc=d3e32559-109319 + Details
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- Definition Amount of unrecognized tax benefits pertaining to uncertain tax positions taken in tax returns. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Unrecognized Tax Benefit -URI http://asc.fasb.org/extlink&oid=6527854 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 15A -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=6907707&loc=SL6600010-109319 + Details
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