Quarterly report pursuant to Section 13 or 15(d)

Mandatorily Redeemable Preferred Stock - Additional Information (Detail)

v2.4.1.9
Mandatorily Redeemable Preferred Stock - Additional Information (Detail) (USD $)
1 Months Ended 3 Months Ended
Feb. 29, 2012
Mar. 31, 2015
Dec. 31, 2014
Class of Stock [Line Items]      
Redeemable preferred stock, shares issued   2,150,000us-gaap_PreferredStockSharesIssued 2,150,000us-gaap_PreferredStockSharesIssued
Redeemable preferred stock, par value   $ 0.001us-gaap_PreferredStockParOrStatedValuePerShare $ 0.001us-gaap_PreferredStockParOrStatedValuePerShare
Preferred shares at a redemption price $ 25.00us-gaap_PreferredStockRedemptionPricePerShare    
Preferred Stock redemption term   On or after January 31, 2016, we may redeem the shares at a redemption price of $25.00 per share, plus any accumulated and unpaid dividends to and including the date of redemption.  
Preferred Stock mandatory redemption date Jan. 31, 2017    
Deferred financing costs $ 1,800,000us-gaap_DeferredOfferingCosts    
Carrying value Term Preferred Stock   2,000us-gaap_PreferredStockValue 2,000us-gaap_PreferredStockValue
Mandatorily Redeemable Preferred Stock [Member]      
Class of Stock [Line Items]      
Redeemable preferred stock, shares issued 1,540,000us-gaap_PreferredStockSharesIssued
/ us-gaap_ScheduleOfSharesSubjectToMandatoryRedemptionBySettlementTermsAxis
= us-gaap_MandatorilyRedeemablePreferredStockMember
   
Redeemable preferred stock, par value $ 0.001us-gaap_PreferredStockParOrStatedValuePerShare
/ us-gaap_ScheduleOfSharesSubjectToMandatoryRedemptionBySettlementTermsAxis
= us-gaap_MandatorilyRedeemablePreferredStockMember
   
Public offering price $ 25.00good_PublicOfferingPrice
/ us-gaap_ScheduleOfSharesSubjectToMandatoryRedemptionBySettlementTermsAxis
= us-gaap_MandatorilyRedeemablePreferredStockMember
   
Gross proceeds of the offering 38,500,000us-gaap_ProceedsFromIssuanceOfPreferredStockAndPreferenceStock
/ us-gaap_ScheduleOfSharesSubjectToMandatoryRedemptionBySettlementTermsAxis
= us-gaap_MandatorilyRedeemablePreferredStockMember
   
Net proceeds, after deducting offering expenses 36,700,000good_NetProceedsAfterDeductingOfferingExpenses
/ us-gaap_ScheduleOfSharesSubjectToMandatoryRedemptionBySettlementTermsAxis
= us-gaap_MandatorilyRedeemablePreferredStockMember
   
Fair value of Term Preferred Stock   39,900,000us-gaap_MandatorilyRedeemablePreferredStockFairValueDisclosure
/ us-gaap_ScheduleOfSharesSubjectToMandatoryRedemptionBySettlementTermsAxis
= us-gaap_MandatorilyRedeemablePreferredStockMember
 
Carrying value Term Preferred Stock   $ 38,500,000us-gaap_PreferredStockValue
/ us-gaap_ScheduleOfSharesSubjectToMandatoryRedemptionBySettlementTermsAxis
= us-gaap_MandatorilyRedeemablePreferredStockMember
$ 38,500,000us-gaap_PreferredStockValue
/ us-gaap_ScheduleOfSharesSubjectToMandatoryRedemptionBySettlementTermsAxis
= us-gaap_MandatorilyRedeemablePreferredStockMember
Closing price of Term Preferred Stock   $ 25.92us-gaap_SharePrice
/ us-gaap_ScheduleOfSharesSubjectToMandatoryRedemptionBySettlementTermsAxis
= us-gaap_MandatorilyRedeemablePreferredStockMember
 
Series C Preferred Stock [Member]      
Class of Stock [Line Items]      
Redeemable preferred stock, dividend rate percentage 7.125%us-gaap_PreferredStockDividendRatePercentage
/ us-gaap_StatementClassOfStockAxis
= us-gaap_SeriesCPreferredStockMember
   
Series C Preferred Stock [Member] | Mandatorily Redeemable Preferred Stock [Member]      
Class of Stock [Line Items]      
Redeemable preferred stock, shares issued   1,540,000us-gaap_PreferredStockSharesIssued
/ us-gaap_ScheduleOfSharesSubjectToMandatoryRedemptionBySettlementTermsAxis
= us-gaap_MandatorilyRedeemablePreferredStockMember
/ us-gaap_StatementClassOfStockAxis
= us-gaap_SeriesCPreferredStockMember
1,540,000us-gaap_PreferredStockSharesIssued
/ us-gaap_ScheduleOfSharesSubjectToMandatoryRedemptionBySettlementTermsAxis
= us-gaap_MandatorilyRedeemablePreferredStockMember
/ us-gaap_StatementClassOfStockAxis
= us-gaap_SeriesCPreferredStockMember
Redeemable preferred stock, par value   $ 0.001us-gaap_PreferredStockParOrStatedValuePerShare
/ us-gaap_ScheduleOfSharesSubjectToMandatoryRedemptionBySettlementTermsAxis
= us-gaap_MandatorilyRedeemablePreferredStockMember
/ us-gaap_StatementClassOfStockAxis
= us-gaap_SeriesCPreferredStockMember
$ 0.001us-gaap_PreferredStockParOrStatedValuePerShare
/ us-gaap_ScheduleOfSharesSubjectToMandatoryRedemptionBySettlementTermsAxis
= us-gaap_MandatorilyRedeemablePreferredStockMember
/ us-gaap_StatementClassOfStockAxis
= us-gaap_SeriesCPreferredStockMember