Investments in Wholly-Owned Properties - Summary (Detail Textuals) $ in Millions	Jun. 30, 2017 USD ($)	Dec. 31, 2016 USD ($) Property
Real Estate Properties [Line Items]
Undeveloped land parcels	$ 45.5	$ 38.5
Under Development
Real Estate Properties [Line Items]
Undeveloped land parcels	$ 71.8	$ 61.2
Wholly-owned properties
Real Estate Properties [Line Items]
Number of real estate properties, held for sale | Property		1