Variable Interest Entities - Summarized Balance Sheet (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Assets:
Net Investment in Real Estate	$ 2,697,975	$ 2,588,422
Total Assets	2,927,826	2,793,263
Liabilities and Partners' Capital:
Mortgage Loans Payable, Net	452,551	495,956
Total Liabilities and Equity/Partners' Capital	2,927,826	2,793,263
Other Real Estate Partnerships
Assets:
Net Investment in Real Estate	279,626	278,398
Other Assets, Net	23,976	24,401
Total Assets	303,602	302,799
Liabilities and Partners' Capital:
Mortgage Loans Payable, Net	61,586	70,366
Other Liabilities, Net	9,602	9,138
Partners’ Capital	232,414	223,295
Total Liabilities and Equity/Partners' Capital	$ 303,602	$ 302,799