XML 78 R66.htm IDEA: XBRL DOCUMENT
v2.4.1.9

Income Taxes (Rollforward of Valuation Allowances) (Details) (USD $) In Thousands, unless otherwise specified | 12 Months Ended
--- | ---
Dec. 31, 2014 | Dec. 31, 2013
Income Tax Disclosure [Abstract] |  |
Valuation allowance at beginning of the year | $ 0 us-gaap_DeferredTaxAssetsValuationAllowance | $ 0 us-gaap_DeferredTaxAssetsValuationAllowance
BioFuel valuation allowance at the Transaction Date | 65,020 grbk_ValuationAllowanceDeferredTaxAssetIncreaseAmount | 0 grbk_ValuationAllowanceDeferredTaxAssetIncreaseAmount
Release of valuation allowance at Transaction Date | (63,859)grbk_ValuationAllowanceDeferredTaxAssetDecreaseAmount | 0 grbk_ValuationAllowanceDeferredTaxAssetDecreaseAmount
Valuation allowance at end of the year | $ 1,161 us-gaap_DeferredTaxAssetsValuationAllowance | $ 0 us-gaap_DeferredTaxAssetsValuationAllowance

X
- Definition Valuation Allowance, Deferred Tax Asset, Decrease, Amount + References No definition available. + Details
Name: | grbk_ValuationAllowanceDeferredTaxAssetDecreaseAmount
Namespace Prefix: | grbk_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Valuation Allowance, Deferred Tax Asset, Increase, Amount + References No definition available. + Details
Name: | grbk_ValuationAllowanceDeferredTaxAssetIncreaseAmount
Namespace Prefix: | grbk_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- 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
Name: | us-gaap_DeferredTaxAssetsValuationAllowance
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Details
Name: | us-gaap_IncomeTaxDisclosureAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration