XML 184 R170.htm IDEA: XBRL DOCUMENT
v3.8.0.1

Income Tax - Movements of Deferred Income Tax Assets and Liabilities (Detail) - TWD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015
Income tax [Line Items] |  |  |
Recognized in Profit or Loss | $ 101 | $ (1,404) | $ 222
Recognized in Other Comprehensive Income | 347 | 349 | 37
Deferred tax asset [Member] |  |  |
Income tax [Line Items] |  |  |
Beginning balance | 2,322 | 2,061 | 1,826
Recognized in Profit or Loss | 64 | (86) | 192
Recognized in Other Comprehensive Income | 344 | 347 | 39
From Business Combination |  |  | 4
Ending balance | 2,730 | 2,322 | 2,061
Deferred tax asset [Member] | Present value of funded defined benefit obligation [Member] |  |  |
Income tax [Line Items] |  |  |
Beginning balance | 1,374 | 1,206 | 1,096
Recognized in Profit or Loss | 5 | (179) | 71
Recognized in Other Comprehensive Income | 344 | 347 | 39
Ending balance | 1,723 | 1,374 | 1,206
Deferred tax asset [Member] | Share of profits of associates and joint ventures accounted for using equity method [Member] |  |  |
Income tax [Line Items] |  |  |
Beginning balance | 330 | 325 | 277
Recognized in Profit or Loss | 1 | 5 | 48
Ending balance | 331 | 330 | 325
Deferred tax asset [Member] | Allowance for doubtful accounts [Member] |  |  |
Income tax [Line Items] |  |  |
Beginning balance | 230 | 169 | 114
Recognized in Profit or Loss | 59 | 61 | 55
Ending balance | 289 | 230 | 169
Deferred tax asset [Member] | Impairment loss on property, plant and equipment [Member] |  |  |
Income tax [Line Items] |  |  |
Beginning balance | 122 | 44 | 32
Recognized in Profit or Loss | (10) | 78 | 12
Ending balance | 112 | 122 | 44
Deferred tax asset [Member] | Deferred revenue [Member] |  |  |
Income tax [Line Items] |  |  |
Beginning balance | 117 | 136 | 156
Recognized in Profit or Loss | (11) | (19) | (20)
Ending balance | 106 | 117 | 136
Deferred tax asset [Member] | Valuation loss on inventory [Member] |  |  |
Income tax [Line Items] |  |  |
Beginning balance | 20 | 33 | 41
Recognized in Profit or Loss | 3 | (13) | (8)
Ending balance | 23 | 20 | 33
Deferred tax asset [Member] | Accrued award credits liabilities [Member] |  |  |
Income tax [Line Items] |  |  |
Beginning balance | 20 | 22 | 28
Recognized in Profit or Loss | (5) | (2) | (6)
Ending balance | 15 | 20 | 22
Deferred tax asset [Member] | Warranties [Member] |  |  |
Income tax [Line Items] |  |  |
Beginning balance | 19 | 18 | 19
Recognized in Profit or Loss | 3 | 1 | (1)
Ending balance | 22 | 19 | 18
Deferred tax asset [Member] | Property, plant and equipment [member] |  |  |
Income tax [Line Items] |  |  |
Beginning balance | 2 | 2 | 0
From Business Combination |  |  | 2
Ending balance | 2 | 2 | 2
Deferred tax asset [Member] | Unrealised foreign exchange gains (losses) [Member] |  |  |
Income tax [Line Items] |  |  |
Beginning balance | 0 | 18 | 0
Recognized in Profit or Loss | 17 | (18) | 18
Ending balance | 17 | 0 | 18
Deferred tax asset [Member] | Others [Member] |  |  |
Income tax [Line Items] |  |  |
Beginning balance | 34 | 40 | 34
Recognized in Profit or Loss | (5) | (6) | 6
Ending balance | 29 | 34 | 40
Deferred tax asset [Member] | Temporary differences [Member] |  |  |
Income tax [Line Items] |  |  |
Beginning balance | 2,268 | 2,013 | 1,797
Recognized in Profit or Loss | 72 | (92) | 175
Recognized in Other Comprehensive Income | 344 | 347 | 39
From Business Combination |  |  | 2
Ending balance | 2,684 | 2,268 | 2,013
Deferred tax asset [Member] | Unused tax losses [Member] |  |  |
Income tax [Line Items] |  |  |
Beginning balance | 54 | 48 | 29
Recognized in Profit or Loss | (8) | 6 | 17
From Business Combination |  |  | 2
Ending balance | 46 | 54 | 48
Deferred tax asset [Member] | Trade-in right [Member] |  |  |
Income tax [Line Items] |  |  |
Beginning balance | 0 |  |
Recognized in Profit or Loss | 15 |  |
Ending balance | 15 | 0 |
Deferred tax liability [Member] |  |  |
Income tax [Line Items] |  |  |
Beginning balance | (1,464) | (148) | (132)
Recognized in Profit or Loss | 31 | (1,318) | 30
Recognized in Other Comprehensive Income | 3 | 2 | (2)
From Business Combination |  |  | (44)
Ending balance | (1,430) | (1,464) | (148)
Deferred tax liability [Member] | Present value of funded defined benefit obligation [Member] |  |  |
Income tax [Line Items] |  |  |
Beginning balance | (1,269) | (1) | 0
Recognized in Profit or Loss | 4 | (1,268) | (1)
Ending balance | (1,265) | (1,269) | (1)
Deferred tax liability [Member] | Unrealised foreign exchange gains (losses) [Member] |  |  |
Income tax [Line Items] |  |  |
Beginning balance | (10) | (1) | (29)
Recognized in Profit or Loss | 10 | (9) | 28
Ending balance | 0 | (10) | (1)
Deferred tax liability [Member] | Others [Member] |  |  |
Income tax [Line Items] |  |  |
Beginning balance | (1) | (1) | 0
Recognized in Profit or Loss | 0 | 0 | (1)
Ending balance | (1) | (1) | (1)
Deferred tax liability [Member] | Land value incremental tax [Member] |  |  |
Income tax [Line Items] |  |  |
Beginning balance | (95) | (95) | (95)
Ending balance | (95) | (95) | (95)
Deferred tax liability [Member] | Deferred revenue for award credits [Member] |  |  |
Income tax [Line Items] |  |  |
Beginning balance | (46) | (2) | (5)
Recognized in Profit or Loss | 17 | (44) | 3
Ending balance | (29) | (46) | (2)
Deferred tax liability [Member] | Intangible assets and goodwill [member] |  |  |
Income tax [Line Items] |  |  |
Beginning balance | (40) | (43) | 0
Recognized in Profit or Loss | 1 | 3 | 1
From Business Combination |  |  | (44)
Ending balance | (39) | (40) | (43)
Deferred tax liability [Member] | Valuation gain or loss on financial instruments, net [Member] |  |  |
Income tax [Line Items] |  |  |
Beginning balance | (3) | (5) | (3)
Recognized in Profit or Loss | (1) | 0 | 0
Recognized in Other Comprehensive Income | 3 | 2 | (2)
Ending balance | $ (1) | $ (3) | $ (5)

X
- Definition Income tax. + References No definition available. + Details
Name: | cht_IncomeTaxLineItems
Namespace Prefix: | cht_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition The amount of tax expense or income relating to changes in deferred tax liabilities and deferred tax assets, recognised in profit or loss. [Refer: Deferred tax assets; Deferred tax expense (income); Deferred tax liabilities] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 12 -IssueDate 2016-01-13 -Paragraph 81 -Subparagraph g -Clause ii -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=12&date=2016-03-30&anchor=para_81_g_ii&doctype=Standard -URIDate 2016-03-31 + Details
Name: | ifrs-full_DeferredTaxExpenseIncomeRecognisedInProfitOrLoss
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:monetaryItemType
Balance Type: | na
Period Type: | duration

X
- Definition The amount of deferred tax liabilities or assets. [Refer: Deferred tax liabilities; Deferred tax assets] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 12 -IssueDate 2016-01-13 -Paragraph 81 -Subparagraph g -Clause i -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=12&date=2016-03-30&anchor=para_81_g_i&doctype=Standard -URIDate 2016-03-31 + Details
Name: | ifrs-full_DeferredTaxLiabilityAsset
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition The amount of income tax relating to amounts recognised in other comprehensive income. [Refer: Other comprehensive income] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 12 -IssueDate 2016-01-13 -Paragraph 81 -Subparagraph ab -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=12&date=2016-03-30&anchor=para_81_ab&doctype=Standard -URIDate 2016-03-31 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 1 -IssueDate 2016-01-13 -Paragraph 90 -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2016-03-30&anchor=para_90&doctype=Standard -URIDate 2016-03-31 + Details
Name: | ifrs-full_IncomeTaxRelatingToComponentsOfOtherComprehensiveIncome
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:monetaryItemType
Balance Type: | na
Period Type: | duration

X
- Definition The increase (decrease) in deferred tax liability (asset) resulting from business combinations. [Refer: Deferred tax liability (asset)] + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Name IAS -Number 12 -IssueDate 2016-01-13 -Paragraph 81 -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=12&date=2016-03-30&anchor=para_81&doctype=Standard -URIDate 2016-03-31 + Details
Name: | ifrs-full_IncreaseDecreaseThroughBusinessCombinationsDeferredTaxLiabilityAsset
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Details
Name: | ifrs-full_AssetsAndLiabilitiesAxis=cht_DeferredTaxAssetMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_TemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsAxis=ifrs-full_PresentValueOfDefinedBenefitObligationMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_TemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsAxis=cht_ShareOfNetProfitOfAssociatesAndJointVenturesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_TemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsAxis=ifrs-full_AllowanceForCreditLossesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_TemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsAxis=cht_ImpairmentLossOfPropertyPlantAndEquipmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_TemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsAxis=cht_DeferredRevenueMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_TemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsAxis=cht_ValuationLossOnInventoryMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_TemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsAxis=cht_AccruedAwardCreditsLiabilitiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_TemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsAxis=ifrs-full_WarrantyProvisionMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_TemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsAxis=ifrs-full_PropertyPlantAndEquipmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_TemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsAxis=ifrs-full_UnrealisedForeignExchangeGainsLossesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_TemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsAxis=ifrs-full_OtherTemporaryDifferencesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_TemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsAxis=ifrs-full_TemporaryDifferenceMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_TemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsAxis=ifrs-full_UnusedTaxLossesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_TemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsAxis=cht_TradeInRightMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_AssetsAndLiabilitiesAxis=cht_DeferredTaxLiabilityMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_TemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsAxis=cht_LandValueIncrementalTaxMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_TemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsAxis=cht_DeferredRevenueForAwardCreditsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_TemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsAxis=ifrs-full_IntangibleAssetsAndGoodwillMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_TemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsAxis=cht_ValuationGainOrLossOnFinancialInstrumentsNetMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |