Consolidated Balance Sheets (Parenthetical) - $ / shares	Mar. 31, 2018	Dec. 31, 2017
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	500,000,000	500,000,000
Common stock, shares issued (in shares)	181,943,725	181,440,051
Common stock, shares outstanding (in shares)	181,943,725	181,440,051
Operating Partnership
General partners' capital account, units issued (in units)	181,943,725	181,440,051
General partners' capital account, units outstanding (in units)	181,943,725	181,440,051
Limited partners' capital account, units issued (in units)	5,464,217	5,364,632
Limited partners' capital account, units outstanding (in units)	5,464,217	5,364,632