Related Party Transactions (by Category) (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Related Party Transaction [Line Items]
Due to Affiliates	$ 6,538		$ 10,252
The Advisor \| Issuer Costs- the Advisor
Related Party Transaction [Line Items]
Expenses from transactions with related party	29	$ 16
Due to Affiliates	9		26
The Advisor \| Disposition Fee- the Advisor
Related Party Transaction [Line Items]
Expenses from transactions with related party	0	1,839
Due to Affiliates	0		2,585
The Advisor \| Other Fees
Related Party Transaction [Line Items]
Expenses from transactions with related party	1,467	1,407
Due to Affiliates	947		1,952
The Advisor and Affiliate of Hines \| Asset Management Fee- the Advisor and affiliates of Hines
Related Party Transaction [Line Items]
Expenses from transactions with related party	8,859	9,366
Due to Affiliates	2,704		2,430
Hines \| Property Management Fee- Hines
Related Party Transaction [Line Items]
Expenses from transactions with related party	1,531	1,835
Due to Affiliates	167		146
Hines \| Development/Construction Management Fee- Hines
Related Party Transaction [Line Items]
Expenses from transactions with related party	483	198
Due to Affiliates	662		207
Hines \| Leasing Fee- Hines
Related Party Transaction [Line Items]
Expenses from transactions with related party	306	362
Due to Affiliates	1,718		2,129
Hines \| Expense Reimbursement- Hines (with respect to management and operations of the Company’s properties)
Related Party Transaction [Line Items]
Expenses from transactions with related party	2,447	$ 2,858
Due to Affiliates	$ 331		$ 777

Receivables to be collected from (obligations owed to) related parties, net as of the balance sheet date where one party can exercise control or significant influence over another party; including affiliates, owners or officers and their immediate families, pension trusts, and so forth.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 850
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=6457730&loc=d3e39549-107864

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(k)(1))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

+ Details

Name:	us-gaap_RelatedPartyTransactionDueFromToRelatedParty
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Expenses recognized resulting from transactions (excluding transactions that are eliminated in consolidated or combined financial statements) with related party.

+ References

+ Details

Name:	us-gaap_RelatedPartyTransactionExpensesFromTransactionsWithRelatedParty
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

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

- Details

Name:	us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=hgri_AdvisorMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RelatedPartyTransactionAxis=hgri_IssuerCostsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RelatedPartyTransactionAxis=hgri_DispositionFeeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RelatedPartyTransactionAxis=hgri_OtherFeesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=hgri_TheAdvisorandAffiliateofHinesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RelatedPartyTransactionAxis=hgri_AssetManagementFeeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=hgri_HinesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RelatedPartyTransactionAxis=hgri_PropertyManagementFeesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RelatedPartyTransactionAxis=hgri_ConstructionManagementFeesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RelatedPartyTransactionAxis=hgri_LeasingFeesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RelatedPartyTransactionAxis=hgri_ExpenseReimbursementsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: