Earnings Per Share (Narrative) (Details) - shares
shares in Thousands
3 Months Ended
Mar. 31, 2018
Mar. 31, 2017
Schedule of Earnings per Share [Line Items]    
Weighted average number shares outstanding – basic (in shares) 304,158 304,569
OP Units    
Schedule of Earnings per Share [Line Items]    
Weighted average number shares outstanding – basic (in shares)   300