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v3.8.0.1

Post-Retirement Liabilities - Summary of Average Periods of the Obligations Under the Benefit Plans (Detail) | 12 Months Ended
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Dec. 31, 2017
Plan A [member] |
Disclosure of Information About Maturity Profile of Defined Benefit Obligation [Line Items] |
Average periods of maturity of the obligations under the benefit plans | 9 years 3 months 11 days
Plan B [member] |
Disclosure of Information About Maturity Profile of Defined Benefit Obligation [Line Items] |
Average periods of maturity of the obligations under the benefit plans | 11 years 6 months 18 days
Health plan [member] |
Disclosure of Information About Maturity Profile of Defined Benefit Obligation [Line Items] |
Average periods of maturity of the obligations under the benefit plans | 13 years 8 months 5 days
Dental plan [member] |
Disclosure of Information About Maturity Profile of Defined Benefit Obligation [Line Items] |
Average periods of maturity of the obligations under the benefit plans | 13 years 8 months 5 days
Life insurance [member] |
Disclosure of Information About Maturity Profile of Defined Benefit Obligation [Line Items] |
Average periods of maturity of the obligations under the benefit plans | 11 years 6 months 18 days

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- Definition Disclosure of Information About Maturity Profile of Defined Benefit Obligation [Line Items] + References No definition available. + Details
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- Definition Total maturity period of defined benefit plans. + References No definition available. + Details
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- Details
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- Details
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- Details
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- Details
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- Details
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