Real Estate and Intangible Assets - Summary of Properties Acquired (Detail) (USD $) In Thousands, unless otherwise specified
|
3 Months Ended |
Mar. 31, 2015
sqft
|
Mar. 31, 2014
sqft
|
Business Acquisition [Line Items] |
|
|
Square Footage (unaudited) |
186,834good_AreaOfRealEstateProperties
|
41,509good_AreaOfRealEstateProperties
|
Total Purchase Price |
$ 28,348good_PurchasePrice
|
$ 10,048good_PurchasePrice
|
Acquisition Expenses |
169good_BusinessAcquisitionExpenses
|
52good_BusinessAcquisitionExpenses
|
Annualized Straight Line Rent |
3,041good_AnnualizedStraightLineRent
|
1,037good_AnnualizedStraightLineRent
|
Debt Issued & Assumed |
14,573us-gaap_MortgageLoansOnRealEstateNewMortgageLoans
|
6,330us-gaap_MortgageLoansOnRealEstateNewMortgageLoans
|
Richardson, TX [Member] |
|
|
Business Acquisition [Line Items] |
|
|
Acquisition Date |
Mar. 06, 2015
|
|
Square Footage (unaudited) |
155,984good_AreaOfRealEstateProperties / us-gaap_BusinessAcquisitionAxis = good_RichardsonTxMember
|
|
Lease Term |
9 years 6 months
|
|
Renewal Options |
2good_NumberOfRenewalOptionUnderLease / us-gaap_BusinessAcquisitionAxis = good_RichardsonTxMember
|
|
Renewal Options Period |
5 years
|
|
Total Purchase Price |
24,700good_PurchasePrice / us-gaap_BusinessAcquisitionAxis = good_RichardsonTxMember
|
|
Acquisition Expenses |
103good_BusinessAcquisitionExpenses / us-gaap_BusinessAcquisitionAxis = good_RichardsonTxMember
|
|
Annualized Straight Line Rent |
2,708good_AnnualizedStraightLineRent / us-gaap_BusinessAcquisitionAxis = good_RichardsonTxMember
|
|
Debt Issued & Assumed |
14,573us-gaap_MortgageLoansOnRealEstateNewMortgageLoans / us-gaap_BusinessAcquisitionAxis = good_RichardsonTxMember
|
|
Birmingham, AL [Member] |
|
|
Business Acquisition [Line Items] |
|
|
Acquisition Date |
Mar. 20, 2015
|
|
Square Footage (unaudited) |
30,850good_AreaOfRealEstateProperties / us-gaap_BusinessAcquisitionAxis = good_BirminghamAlMember
|
|
Lease Term |
8 years 6 months
|
|
Renewal Options |
1good_NumberOfRenewalOptionUnderLease / us-gaap_BusinessAcquisitionAxis = good_BirminghamAlMember
|
|
Renewal Options Period |
5 years
|
|
Total Purchase Price |
3,648good_PurchasePrice / us-gaap_BusinessAcquisitionAxis = good_BirminghamAlMember
|
|
Acquisition Expenses |
66good_BusinessAcquisitionExpenses / us-gaap_BusinessAcquisitionAxis = good_BirminghamAlMember
|
|
Annualized Straight Line Rent |
333good_AnnualizedStraightLineRent / us-gaap_BusinessAcquisitionAxis = good_BirminghamAlMember
|
|
Allen, TX [Member] |
|
|
Business Acquisition [Line Items] |
|
|
Acquisition Date |
|
Mar. 27, 2014
|
Square Footage (unaudited) |
|
21,154good_AreaOfRealEstateProperties / us-gaap_BusinessAcquisitionAxis = good_AllenTXMember
|
Lease Term |
|
12 years
|
Renewal Options |
|
4good_NumberOfRenewalOptionUnderLease / us-gaap_BusinessAcquisitionAxis = good_AllenTXMember
|
Renewal Options Period |
|
5 years
|
Total Purchase Price |
|
5,525good_PurchasePrice / us-gaap_BusinessAcquisitionAxis = good_AllenTXMember
|
Acquisition Expenses |
|
26good_BusinessAcquisitionExpenses / us-gaap_BusinessAcquisitionAxis = good_AllenTXMember
|
Annualized Straight Line Rent |
|
570good_AnnualizedStraightLineRent / us-gaap_BusinessAcquisitionAxis = good_AllenTXMember
|
Debt Issued & Assumed |
|
3,481us-gaap_MortgageLoansOnRealEstateNewMortgageLoans / us-gaap_BusinessAcquisitionAxis = good_AllenTXMember
|
Colleyville, TX [Member] |
|
|
Business Acquisition [Line Items] |
|
|
Acquisition Date |
|
Mar. 27, 2014
|
Square Footage (unaudited) |
|
20,355good_AreaOfRealEstateProperties / us-gaap_BusinessAcquisitionAxis = good_ColleyvilleTxMember
|
Lease Term |
|
12 years
|
Renewal Options |
|
4good_NumberOfRenewalOptionUnderLease / us-gaap_BusinessAcquisitionAxis = good_ColleyvilleTxMember
|
Renewal Options Period |
|
5 years
|
Total Purchase Price |
|
4,523good_PurchasePrice / us-gaap_BusinessAcquisitionAxis = good_ColleyvilleTxMember
|
Acquisition Expenses |
|
26good_BusinessAcquisitionExpenses / us-gaap_BusinessAcquisitionAxis = good_ColleyvilleTxMember
|
Annualized Straight Line Rent |
|
467good_AnnualizedStraightLineRent / us-gaap_BusinessAcquisitionAxis = good_ColleyvilleTxMember
|
Debt Issued & Assumed |
|
$ 2,849us-gaap_MortgageLoansOnRealEstateNewMortgageLoans / us-gaap_BusinessAcquisitionAxis = good_ColleyvilleTxMember
|