Equity, Capital and Other Interests - Issued and Outstanding Preferred Shares and Preference Units (Details) - USD ($) $ / shares in Units, $ in Thousands	6 Months Ended
	Jun. 30, 2018	Dec. 31, 2017
Class Of Stock [Line Items]
8.29% Series K Cumulative Redeemable Preferred; liquidation value $50 per share; 745,600 shares issued and outstanding as of June 30, 2018 and December 31, 2017	$ 37,280	$ 37,280
ERPOP [Member]
Class Of Stock [Line Items]
8.29% Series K Cumulative Redeemable Preferred; liquidation value $50 per share; 745,600 shares issued and outstanding as of June 30, 2018 and December 31, 2017	$ 37,280	37,280
Preferred Stock
Class Of Stock [Line Items]
Preferred Stocks Preference Units Call Date	Dec. 10, 2026
Annual Dividend Per Preferred Share Preference Unit	$ 4.145
8.29% Series K Cumulative Redeemable Preferred; liquidation value $50 per share; 745,600 shares issued and outstanding as of June 30, 2018 and December 31, 2017	$ 37,280	37,280
Preferred Stock | ERPOP [Member]
Class Of Stock [Line Items]
Preferred Stocks Preference Units Call Date	Dec. 10, 2026
Annual Dividend Per Preferred Share Preference Unit	$ 4.145
8.29% Series K Cumulative Redeemable Preferred; liquidation value $50 per share; 745,600 shares issued and outstanding as of June 30, 2018 and December 31, 2017	$ 37,280	$ 37,280