Summary of Significant Accounting Policies - Condensed Balance Sheets (Detail) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Assets:
Net Investment in Real Estate	$ 2,393,078	$ 2,396,391
Total Assets	2,583,074	2,592,708
Liabilities and Partners' Capital:
Mortgage Loans Payable, Net	593,976	599,985
Partners’ Capital	1,096,535	1,100,510
Total Liabilities and Partners’ Capital	2,583,074	2,592,708
Other Real Estate Partnerships
Assets:
Net Investment in Real Estate	284,155	278,720
Other Assets, Net	19,450	21,078
Total Assets	303,605	299,798
Liabilities and Partners' Capital:
Mortgage Loans Payable, Net	80,431	81,231
Other Liabilities, Net	22,293	10,656
Partners’ Capital	200,881	207,911
Total Liabilities and Partners’ Capital	$ 303,605	$ 299,798