v3.3.1.900
Subsequent Events (Details) - $ / shares
12 Months Ended
Feb. 15, 2016
Nov. 04, 2015
Dec. 31, 2015
Dec. 31, 2014
Dec. 31, 2013
Subsequent Event [Line Items]          
Dividends declared per common share (in dollars per share)   $ 0.14 $ 0.53 $ 0.46 $ 0.38
Subsequent event          
Subsequent Event [Line Items]          
Dividends declared per common share (in dollars per share) $ 0.14        
Subsequent event | Preference shares - Series A          
Subsequent Event [Line Items]          
Dividends declared per Preference share (in dollars per share) 0.515625        
Subsequent event | Preference shares - Series B          
Subsequent Event [Line Items]          
Dividends declared per Preference share (in dollars per share) 0.90625        
Subsequent event | Preference shares - Series C          
Subsequent Event [Line Items]          
Dividends declared per Preference share (in dollars per share) $ 0.54427083