Commitments and Contingencies - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Commitments and Contingencies
Contingent liabilities for construction performance	$ 4.3	$ 34.8
Rental Revenues | Hampton Roads Properties
Commitments and Contingencies
Concentrations of credit risk	48.00%	53.00%	53.00%
Rental Revenues | Town Center Properties
Commitments and Contingencies
Concentrations of credit risk	31.00%	38.00%	38.00%
Operating Partnership
Commitments and Contingencies
Outstanding letters of credit	$ 9.5	$ 2.1
Group Of Three Construction Customers | General Contracting and Real Estate Services Revenues
Commitments and Contingencies
Concentrations of credit risk	67.00%	55.00%	41.00%
Group Of Three Construction Customers | General Contracting and Real Estate Services Segment Profit
Commitments and Contingencies
Concentrations of credit risk	66.00%	28.00%	20.00%