Real Estate Joint Ventures - Summarized Financial Information for Unconsolidated Investments (Details) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014	Sep. 30, 2014	Dec. 31, 2013
Investment In Unconsolidated Affiliates [Line Items]
Cash and cash equivalents	$ 157,887	$ 34,515	$ 61,582	$ 21,894
Other assets	32,647	31,990
Total assets	1,012,456	1,303,135
Equity	668,709	971,209
Total liabilities and equity	1,012,456	1,303,135
Other Affiliates
Investment In Unconsolidated Affiliates [Line Items]
Cash and cash equivalents	14,362	15,461
Other assets	58	57
Total assets	14,420	15,518
Accounts payable and other liabilities	1,103	605
Equity	13,317	14,913
Total liabilities and equity	$ 14,420	$ 15,518