Real Estate Joint Ventures - Summarized Financial Information for Unconsolidated Investments (Details) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015	Sep. 30, 2015	Dec. 31, 2014
Investments in and Advances to Affiliates [Line Items]
Cash and cash equivalents	$ 165,286	$ 212,773	$ 157,887	$ 34,515
Other assets	33,343	36,573
Total assets	986,429	982,742
Equity	665,333	665,263
Total liabilities and equity	986,429	982,742
Other affiliates
Investments in and Advances to Affiliates [Line Items]
Cash and cash equivalents	12,796	13,760
Other assets	59	58
Total assets	12,855	13,818
Accounts payable and other liabilities	1,535	1,978
Equity	11,320	11,840
Total liabilities and equity	$ 12,855	$ 13,818