Consolidated Balance Sheets (Parenthetical) - $ / shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Common stock, par value per share	$ 0.01	$ 0.01
Common stock, shares authorized	145,000,000	145,000,000
Common stock, shares issued	114,246,393	113,844,267
Common stock, shares outstanding	114,246,393	113,844,267
Preferred Stock, Par or Stated Value Per Share	$ 0.01	$ 0.01
Preferred Stock, Shares Authorized	20,000,000	20,000,000
Preferred Stock, Dividend Rate, Percentage	8.50%	8.50%
Preferred Stock, Shares Issued	867,846	867,846
Preferred Stock, Shares Outstanding	867,846	867,846
Preferred Stock, Liquidation Preference Per Share	$ 50.00	$ 50.00
Redeemable stock, shares issued and outstanding	107,162	98,371
General Partners' Capital Account, Units Outstanding	114,246,393	113,844,267
Limited Partners' Capital Account, Units Outstanding	4,067,174	4,111,301
Limited Partner [Member]
Redeemable stock, shares issued and outstanding	107,162	98,371
General Partners' Capital Account, Units Outstanding	114,246,393	113,844,267
Limited Partners' Capital Account, Units Outstanding	4,067,174	4,111,301
Preferred Units, Issued	867,846	867,846
Preferred Units, Outstanding	867,846	867,846