XML 46 R76.htm IDEA: XBRL DOCUMENT v3.19.3.a.u2
Income Taxes - Roll-forward of Unrecognized Tax Benefits and Associated Accrued Interest and Penalties (Detail) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
Income Tax Contingency [Line Items]      
Opening balance at January 1 $ 14.0 $ 2.5 $ 2.3
Reductions for tax positions of prior periods     0.7
Additions for tax positions of prior periods 2.4 12.1  
Additions for current year tax positions   14.0 0.0
Reductions due to lapsed statute of limitations   (0.6) (0.5)
Closing balance at 31 December 16.4 14.0 2.5
Current 0.0   0.0
Non-current 16.4 14.0 2.5
Interest and Penalties [Member]      
Income Tax Contingency [Line Items]      
Opening balance at January 1 13.4 0.3 2.2
Reductions for tax positions of prior periods     0.5
Additions for tax positions of prior periods 1.0 0.4  
Additions for current year tax positions   13.4 0.0
Reductions due to lapsed statute of limitations   (0.5) (0.5)
Closing balance at 31 December 14.4 13.4 0.3
Current 0.0   0.0
Non-current 14.4   0.3
Unrecognized Tax Benefits [Member]      
Income Tax Contingency [Line Items]      
Opening balance at January 1 0.6 2.2 0.1
Reductions for tax positions of prior periods     0.2
Additions for tax positions of prior periods 1.4 11.7  
Additions for current year tax positions   0.6 0.0
Reductions due to lapsed statute of limitations   (0.1) (0.0)
Closing balance at 31 December 2.0 $ 0.6 2.2
Current 0.0   0.0
Non-current $ 2.0   $ 2.2