Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2015	Dec. 31, 2014
Common stock, shares outstanding	75,408,571	75,267,675
General partners' capital account, units outstanding	75,408,571	75,267,675
Limited partners' capital account, units outstanding	4,162,996	4,191,152
Parent Company [Member]
Common stock, par value per share	$ 0.01	$ 0.01
Common stock, shares authorized	100,000,000	100,000,000
Common stock, shares issued	75,408,571	75,267,675
Common stock, shares outstanding	75,408,571	75,267,675
Redeemable stock, shares/units issued and outstanding	90,844	87,818
Limited Partner [Member]
Redeemable stock, shares/units issued and outstanding	90,844	87,818
General partners' capital account, units outstanding	75,408,571	75,267,675
Limited partners' capital account, units outstanding	4,162,996	4,191,152

Face amount or stated value per share of common stock.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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