Investment in Unconsolidated Joint Ventures (Cousins W Rio Salado, LLC) (Details) - Cousins W. Rio Salado, LLC ft² in Thousands, $ in Millions	Dec. 31, 2016 ft²	Oct. 31, 2016 USD ($)
Schedule of Equity Method Investments [Line Items]
Ownership interest percentage	74.60%
Square footage of real estate property (square feet) | ft²	225
American Airlines
Schedule of Equity Method Investments [Line Items]
Ownership interest percentage	25.40%
Percentage of building under lease		100.00%
Purchase of interest in the building | $		$ 19.6
ADP
Schedule of Equity Method Investments [Line Items]
Percentage of building under lease		100.00%