XML 78 R63.htm IDEA: XBRL DOCUMENT
v3.6.0.2

Stockholders' Equity and Mezzanine Equity - Dividends Declared (Detail) - $ / shares | 12 Months Ended
--- | ---
Dec. 31, 2016 | Dec. 31, 2015 | Dec. 31, 2014
Senior Common Stock [Member] |  |  |
Dividends Payable [Line Items] |  |  |
Common stock, cash paid (in dollars per share) | $ 1.0500 | $ 1.0500 | $ 1.0500
Series A Preferred Stock [Member] |  |  |
Dividends Payable [Line Items] |  |  |
Preferred stock, cash paid (in dollars per share) | 1.9374996 | 1.9374996 | 1.9374996
Series B Preferred Stock [Member] |  |  |
Dividends Payable [Line Items] |  |  |
Preferred stock, cash paid (in dollars per share) | 1.8750 | 1.8750 | 1.8750
Series C Preferred Stock [Member] |  |  |
Dividends Payable [Line Items] |  |  |
Preferred stock, cash paid (in dollars per share) | 1.1330 | 1.7813 | 1.7813
Series D Preferred Stock [Member] |  |  |
Dividends Payable [Line Items] |  |  |
Preferred stock, cash paid (in dollars per share) | 1.0538 | 0.0000 | 0.0000
Common Stock [Member] |  |  |
Dividends Payable [Line Items] |  |  |
Common stock, cash paid (in dollars per share) | $ 1.500 | $ 1.500 | $ 1.500

X
- Definition Aggregate dividends paid during the period for each share of common stock outstanding. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.3-04) -URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770 + Details
Name: | us-gaap_CommonStockDividendsPerShareCashPaid
Namespace Prefix: | us-gaap_
Data Type: | num:perShareItemType
Balance Type: | na
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_DividendsPayableLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Aggregate dividends paid during the period for each share of preferred stock outstanding. + References No definition available. + Details
Name: | us-gaap_PreferredStockDividendsPerShareCashPaid
Namespace Prefix: | us-gaap_
Data Type: | num:perShareItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_StatementClassOfStockAxis=good_SeniorCommonStockMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementClassOfStockAxis=us-gaap_SeriesAPreferredStockMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementClassOfStockAxis=us-gaap_SeriesBPreferredStockMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementClassOfStockAxis=us-gaap_SeriesCPreferredStockMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementClassOfStockAxis=us-gaap_SeriesDPreferredStockMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementEquityComponentsAxis=us-gaap_CommonStockMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |