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Employee Benefits - Summary of Trust Assets (Detail) | Dec. 31, 2017 | Dec. 31, 2016
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Variable return: |  |
Trust assets fixed and variable return percentage | 100.00% | 100.00%
Traded Securities [member] |  |
Fixed return: |  |
Trust assets fixed return percentage | 18.00% | 15.00%
Bank instruments [member] |  |
Fixed return: |  |
Trust assets fixed return percentage | 5.00% | 4.00%
Federal government instruments of the respective countries [member] |  |
Fixed return: |  |
Trust assets fixed return percentage | 62.00% | 63.00%
Publicly traded shares [member] |  |
Variable return: |  |
Trust assets variable return percentage | 15.00% | 18.00%

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- Definition Fixed return. + References No definition available. + Details
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- Definition Trust assets fixed and variable return percentage. + References No definition available. + Details
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- Definition Trust assets fixed return percentage. + References No definition available. + Details
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- Definition Trust assets variable return percentage. + References No definition available. + Details
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- Definition Variable return. + References No definition available. + Details
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- Details
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Namespace Prefix: |
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Balance Type: |
Period Type: |

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- Details
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Namespace Prefix: |
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Balance Type: |
Period Type: |

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- Details
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Namespace Prefix: |
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Balance Type: |
Period Type: |

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- Details
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Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |