Condensed Consolidated Balance Sheets (Parenthetical) (USD $)	Mar. 31, 2014 Parent Company [Member]	Dec. 31, 2013 Parent Company [Member]	Mar. 31, 2014 Limited Partner [Member]	Dec. 31, 2013 Limited Partner [Member]
General Partners' Capital Account, Units Outstanding			75,009,303	74,830,726
Common stock, par value per share	$ 0.01	$ 0.01
Common stock, shares authorized	100,000,000	100,000,000
Common stock, shares issued	75,009,303	74,830,726
Common stock, shares outstanding	75,009,303	74,830,726
Redeemable stock, shares issued and outstanding	77,312	83,139	77,312	83,139
Limited Partners' Capital Account, Units Outstanding			4,208,526	4,227,384