Equity Investments in Real Estate - Proportionate Share of Income (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Equity Method Investment, Financial Statement, Reported Amounts
Equity in earnings of equity method investments in real estate	$ 1,985	$ 2,172
Equity Method Investments
Equity Method Investment, Financial Statement, Reported Amounts
Equity in earnings of equity method investments in real estate	2,847	3,420
Equity Method Investments | Net Lease
Equity Method Investment, Financial Statement, Reported Amounts
Equity in earnings of equity method investments in real estate	4,955	3,552
Equity Method Investments | All Other
Equity Method Investment, Financial Statement, Reported Amounts
Equity in earnings of equity method investments in real estate	(2,108)	262
Equity Method Investments | Self-Storage
Equity Method Investment, Financial Statement, Reported Amounts
Equity in earnings of equity method investments in real estate	0	(394)
Amortization of Basis Difference on Equity Investments
Equity Method Investment, Financial Statement, Reported Amounts
Equity in earnings of equity method investments in real estate	(862)	(1,248)
Amortization of Basis Difference on Equity Investments | Net Lease
Equity Method Investment, Financial Statement, Reported Amounts
Equity in earnings of equity method investments in real estate	(563)	(820)
Amortization of Basis Difference on Equity Investments | All Other
Equity Method Investment, Financial Statement, Reported Amounts
Equity in earnings of equity method investments in real estate	(299)	(389)
Amortization of Basis Difference on Equity Investments | Self-Storage
Equity Method Investment, Financial Statement, Reported Amounts
Equity in earnings of equity method investments in real estate	$ 0	$ (39)