Annual report pursuant to Section 13 and 15(d)

Capital (Details)

v3.10.0.1
Capital (Details)
$ / shares in Units, $ in Millions
 12 Months Ended
Mar. 16, 2018
USD ($)
$ / shares
Mar. 16, 2017
USD ($)
$ / shares
Dec. 31, 2018
shares
Dec. 31, 2017
shares
Dec. 31, 2016
shares
Class of Stock [Line Items]          
Payments of dividends | $ $ 31.7 $ 10.7      
Sub Shares          
Class of Stock [Line Items]          
Ratio of certificates to sub-shares     0.0003333    
Number of shares repurchased and retired (in shares) | shares     59,185 105,715 190,750
Cash Dividend | Sub Shares          
Class of Stock [Line Items]          
Dividend paid per sub-share (in dollars per share) $ 1.05 $ 0.35      
Special Dividend | Sub Shares          
Class of Stock [Line Items]          
Dividend paid per sub-share (in dollars per share) $ 3 $ 1