XML 83 R61.htm IDEA: XBRL DOCUMENT v3.20.2
Fair value measurements - Financial instruments disclosed, but not carried at fair value (Details) - USD ($)
$ in Millions
Sep. 30, 2020
Dec. 31, 2019
Financial instruments not carried at fair value    
Debt $ 695.8 $ 685.2
Carrying Value | Series B preference shares    
Financial instruments not carried at fair value    
Redeemable preference shares 197.5 223.0
2017 SEK Subordinated Notes    
Financial instruments not carried at fair value    
Debt 301.3 291.2
2017 SEK Subordinated Notes | Carrying Value    
Financial instruments not carried at fair value    
Debt 301.3 291.2
2016 SIG Senior Notes    
Financial instruments not carried at fair value    
Debt 394.5 394.0
2016 SIG Senior Notes | Carrying Value    
Financial instruments not carried at fair value    
Debt 394.5 394.0
Level 3 Inputs | Fair Value | Series B preference shares    
Financial instruments not carried at fair value    
Redeemable preference shares 244.5 186.4
Level 3 Inputs | 2017 SEK Subordinated Notes | Fair Value    
Financial instruments not carried at fair value    
Debt 298.8 294.5
Level 3 Inputs | 2016 SIG Senior Notes | Fair Value    
Financial instruments not carried at fair value    
Debt $ 394.7 $ 394.5