Real Estate Joint Ventures - Summarized Financial Information for Unconsolidated Investments (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014	Jun. 30, 2014	Dec. 31, 2013
Investment In Unconsolidated Affiliates [Line Items]
Cash and cash equivalents	$ 337,972	$ 34,515	$ 50,883	$ 21,894
Other assets	33,951	31,990
Total assets	1,319,460	1,303,135
Equity	971,371	971,209
Total liabilities and equity	1,319,460	1,303,135
Other Affiliates
Investment In Unconsolidated Affiliates [Line Items]
Cash and cash equivalents	14,790	15,461
Other assets	58	57
Total assets	14,848	15,518
Accounts payable and other liabilities	1,128	605
Equity	13,720	14,913
Total liabilities and equity	$ 14,848	$ 15,518