Investment in Unconsolidated Joint Ventures (Narrative) (Details) ft² in Thousands	3 Months Ended
	Jun. 30, 2018 ft² loan_extension
HICO Avalon II, LLC
Schedule of Equity Method Investments [Line Items]
Area of property (in sq ft) | ft²	251
Predevelopment costs, funding percentage	75.00%
Development costs, funding percentage	90.00%
HICO Avalon II, LLC | Hines II
Schedule of Equity Method Investments [Line Items]
Predevelopment costs, funding percentage	25.00%
Development costs, funding percentage	10.00%
Carolina Square Holdings LP
Schedule of Equity Method Investments [Line Items]
Number of loan extensions | loan_extension	2
Extension period	1 year