Quarterly report pursuant to Section 13 or 15(d)

Subsequent Events (Details)

v3.8.0.1
Subsequent Events (Details) - $ / shares
3 Months Ended 9 Months Ended 12 Months Ended
Oct. 25, 2017
Sep. 30, 2017
Sep. 30, 2016
Sep. 30, 2017
Sep. 30, 2016
Dec. 31, 2016
Subsequent Event [Line Items]            
Dividends declared per share (in dollars per share)   $ 0.750 $ 0.75 $ 2.250 $ 2.25  
Common Stock [Member] | Subsequent Event [Member]            
Subsequent Event [Line Items]            
Dividends declared per share (in dollars per share) $ 0.75          
Series A Cumulative Redeemable Preferred Stock [Member]            
Subsequent Event [Line Items]            
Coupon rate percentage       7.375%   7.375%
Series A Cumulative Redeemable Preferred Stock [Member] | Depositary Shares [Member] | Subsequent Event [Member]            
Subsequent Event [Line Items]            
Depositary stock, dividends declared per share (in dollars per share) $ 0.4609375          
Series A Cumulative Redeemable Preferred Stock [Member] | Preferred Stock [Member]            
Subsequent Event [Line Items]            
Coupon rate percentage       7.375%