XML 62 R39.htm IDEA: XBRL DOCUMENT v3.10.0.1

Real Estate and Intangible Assets - Schedule of Revenue and Earnings Recognized on Properties Acquired (Detail) - Asset Acquisitions $ in Thousands	12 Months Ended
	Dec. 31, 2016 USD ($) acquisition
Business Acquisition [Line Items]
Number of acquisitions completed | acquisition	2
Rental Revenue	$ 1,462
Earnings	$ 162

X

- Definition

Net income loss from acquired properties.

+ References

No definition available.

+ Details

Name:	good_NetIncomeLossFromAcquiredProperties
Namespace Prefix:	good_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

X

- Definition

Number of acquisitions completed.

+ References

No definition available.

+ Details

Name:	good_NumberOfAcquisitionsCompleted
Namespace Prefix:	good_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Operating leases income statement lease revenue from acquired properties.

+ References

No definition available.

+ Details

Name:	good_OperatingLeasesIncomeStatementLeaseRevenueFromAcquiredProperties
Namespace Prefix:	good_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

X

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_BusinessAcquisitionLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

X

- Details

Name:	us-gaap_BusinessAcquisitionAxis=good_AssetAcquisitionsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: