Variable Interest Entities - Summarized Balance Sheet (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
ASSETS
Net Investment in Real Estate	$ 2,705,826	$ 2,588,422
Total Assets	2,941,062	2,793,263
LIABILITIES AND PARTNERS' CAPITAL
Mortgage Loans Payable, Net	450,056	495,956
Total Liabilities and Equity/Partners' Capital	2,941,062	2,793,263
Other Real Estate Partnerships
ASSETS
Net Investment in Real Estate	270,708	278,398
Other Assets, Net	23,530	24,401
Total Assets	294,238	302,799
LIABILITIES AND PARTNERS' CAPITAL
Mortgage Loans Payable, Net	61,256	70,366
Other Liabilities, Net	9,283	9,138
Partners' Capital	223,699	223,295
Total Liabilities and Equity/Partners' Capital	$ 294,238	$ 302,799