Commitments and Contingencies (Details) $ in Millions		1 Months Ended	12 Months Ended
	Jul. 23, 2015	Apr. 30, 2015 USD ($) ft²	Dec. 31, 2015 USD ($)
Commitments and Contingencies.
Percentage of operating partnership units that are disposed in certain taxable transactions			90.00
Development costs, cumulative		$ 30.0
Capital expenditures incurred but not yet paid		$ 18.1
Area of land | ft²		136,580
Alleged losses	$70,080,000
Loss contingency, damages sought	$802,564
Other expenses
Open commitments related to construction contracts			$ 77.2
Open commitments related to telecommunications contracts			16.3
Estimated litigation liability			2.8
Minimum
Other expenses
Estimated litigation liability			0.0
Maximum
Other expenses
Estimated litigation liability			3.0
Commonwealth Of Virginia | Minimum
Commitments and Contingencies.
Unrecorded sales and use tax payable			0.0
Commonwealth Of Virginia | Maximum
Commitments and Contingencies.
Sales and use tax payable if certain threasholds are not met			7.5
Unrecorded sales and use tax payable			$ 1.0