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Post-Retirement Benefits - Additional Information (Detail) - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2018
Dec. 31, 2017
Multi-employer defined benefit plans [member] | Medical benefits plan subsidiaries abroad [member]    
Disclosure of summary of retirement benefit plans other benefits post retirement [line items]    
Defined contribution pension plan by employer $ 14.1 $ 22.2