XML 365 R123.htm IDEA: XBRL DOCUMENT v3.10.0.1
Tax - Summary of Unrecognized Deferred Tax Based on Expiry Date (Detail) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2018
Dec. 31, 2017
Unrecognised deferred tax position [line items]    
Unrecognised deferred tax $ 163 $ 184
2021 [member]    
Unrecognised deferred tax position [line items]    
Gross carrying amount 28 21
Unrecognised deferred tax 6 5
2022 [member]    
Unrecognised deferred tax position [line items]    
Gross carrying amount 10 11
Unrecognised deferred tax 2 3
2023 [member]    
Unrecognised deferred tax position [line items]    
Gross carrying amount 1 1
Unrecognised deferred tax 0  
2024 [member]    
Unrecognised deferred tax position [line items]    
Gross carrying amount 4 20
Unrecognised deferred tax 0 1
2025 [member]    
Unrecognised deferred tax position [line items]    
Gross carrying amount 92 92
Unrecognised deferred tax 21 23
After 2025 [member]    
Unrecognised deferred tax position [line items]    
Gross carrying amount 46 26
Unrecognised deferred tax $ 3 $ 3