Equity, Capital and Other Interests Preferred (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Class of Stock [Line Items]
Preferred Shares of beneficial interest, $0.01 par value; 100,000,000 shares authorized; 803,600 shares issued and outstanding as of June 30, 2015 and 1,000,000 shares issued and outstanding as of December 31, 2014	$ 40,180		$ 40,180		$ 50,000
Partial redemption of 8.29% Series K Cumulative Redeemable			9,820	$ 0
Premium on redemption of Preference Units	0	$ 0	2,789	0
OPERATING PARTNERSHIP
Class of Stock [Line Items]
Partial redemption of 8.29% Series K Cumulative Redeemable			9,820	0
Premium on redemption of Preference Units	0	$ 0	2,789	$ 0
Preferred Units	$ 40,180		$ 40,180		$ 50,000
Series K Preferred Stock [Member]
Class of Stock [Line Items]
Preferred Stock Preference Units Dividend Rate Percentage			8.29%		8.29%
Preferred Stock Preference Units Redemption Price Per Share Unit	$ 50.00		$ 50.00		$ 50.00
Preferred Stock Preference Units Issued	803,600		803,600		1,000,000
Preferred Stock Preference Units Outstanding	803,600		803,600		1,000,000
Preferred Stocks Preference Units Redemption Date			Dec. 10, 2026
Annual Dividend Per Preferred Share Preference Unit			$ 4.145
Preferred Shares of beneficial interest, $0.01 par value; 100,000,000 shares authorized; 803,600 shares issued and outstanding as of June 30, 2015 and 1,000,000 shares issued and outstanding as of December 31, 2014	$ 40,180		$ 40,180		$ 50,000
Preferred Stock Preference Units Repurchased and Retired			196,400
Partial redemption of 8.29% Series K Cumulative Redeemable			$ 9,820
Payments For Repurchase Of Preferred Stock Preference Units			12,700
Premium on redemption of Preference Units			$ 2,789
Series K Preferred Stock [Member] \| OPERATING PARTNERSHIP
Class of Stock [Line Items]
Preferred Stock Preference Units Dividend Rate Percentage			8.29%		8.29%
Preferred Stock Preference Units Redemption Price Per Share Unit	$ 50.00		$ 50.00		$ 50.00
Preferred Stock Preference Units Issued	803,600		803,600		1,000,000
Preferred Stock Preference Units Outstanding	803,600		803,600		1,000,000
Preferred Stocks Preference Units Redemption Date			Dec. 10, 2026
Annual Dividend Per Preferred Share Preference Unit			$ 4.145
Preferred Units	$ 40,180		$ 40,180		$ 50,000

ERP OPERATING LTD PARTNERSHIP 10-Q