XML 287 R99.htm IDEA: XBRL DOCUMENT v3.19.1
Derivative Financial Instruments - Additional Information (Detail) - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2018
Dec. 31, 2017
Fair value hedges [member]    
Disclosure of detailed information about financial instruments [line items]    
Financial liabilities at amortised cost $ 3,647.6 $ 4,198.3
Financial instruments designated as hedging instruments, at fair value $ 3,648.4 $ 4,198.5
Hedge effectiveness ratio 100.00%  
Hedge effectiveness ratio considering changes in discounted value of hedge instrument 99.44% 99.92%
Cash flow [member]    
Disclosure of detailed information about financial instruments [line items]    
Hedge effectiveness ratio 100.00%  
Hedge effectiveness ratio considering changes in discounted value of hedge instrument 86.79% 97.05%