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Related Parties Transactions - Summary of Related Parties (Detail) | 12 Months Ended
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Dec. 31, 2017
Taiwan International Standard Electronics Co., Ltd. ("TISE") [Member] |
Disclosure of transactions between related parties [Line Items] |
Relationship | Associate
So-net Entertainment Taiwan Limited ("So-net") [Member] |
Disclosure of transactions between related parties [Line Items] |
Relationship | Associate
Skysoft Co., Ltd. ("SKYSOFT") [Member] |
Disclosure of transactions between related parties [Line Items] |
Relationship | Associate
KingwayTek Technology Co., Ltd. ("KWT") [Member] |
Disclosure of transactions between related parties [Line Items] |
Relationship | Associate
Dian Zuan Integrating Marketing Co., Ltd. ("DZIM") [Member] |
Disclosure of transactions between related parties [Line Items] |
Relationship | Associate
Taiwan International Ports Logistics Corporation ("TIPL") [Member] |
Disclosure of transactions between related parties [Line Items] |
Relationship | Associate
Huada Digital Corporation ("HDD") [Member] |
Disclosure of transactions between related parties [Line Items] |
Relationship | Joint venture
Chunghwa Benefit One Co., Ltd. ("CBO") [Member] |
Disclosure of transactions between related parties [Line Items] |
Relationship | Joint venture
International Integrated System, Inc. ("IISI") [Member] |
Disclosure of transactions between related parties [Line Items] |
Relationship | Associate
Senao Networks, Inc. ("SNI") [Member] |
Disclosure of transactions between related parties [Line Items] |
Relationship | Associate
HopeTech Technologies Limited ("HopeTech") [Member] |
Disclosure of transactions between related parties [Line Items] |
Relationship | Associate
EnGenius Tech. Co., Ltd. [Member] |
Disclosure of transactions between related parties [Line Items] |
Relationship | Associate
ST-2 Satellite Ventures Pte., Ltd. ("STS") [Member] |
Disclosure of transactions between related parties [Line Items] |
Relationship | Associate
Viettel-CHT Co., Ltd. ("Viettel-CHT") [Member] |
Disclosure of transactions between related parties [Line Items] |
Relationship | Associate
Click Force Co., Ltd. ("CF") [Member] |
Disclosure of transactions between related parties [Line Items] |
Relationship | Associate
Chunghwa Telecom Foundation [Member] |
Disclosure of transactions between related parties [Line Items] |
Relationship | A nonprofit organization of which the funds donated by Chunghwa exceeds one third of its total funds
Senao Technical and Cultural Foundation [Member] |
Disclosure of transactions between related parties [Line Items] |
Relationship | A nonprofit organization of which the funds donated by SENAO exceeds one third of its total funds
Sochamp Technology Co., Ltd. [Member] |
Disclosure of transactions between related parties [Line Items] |
Relationship | Investor of significant influence over CHST
E-Life Mall Co., Ltd. [Member] |
Disclosure of transactions between related parties [Line Items] |
Relationship | One of the directors of E-Life Mall and a director of SENAO are members of an immediate family
Engenius Technologies Co., Ltd. [Member] |
Disclosure of transactions between related parties [Line Items] |
Relationship | Chairman of Engenius Technologies Co., Ltd. is a member of SENAO’s management
United Daily News Co., Ltd. [Member] |
Disclosure of transactions between related parties [Line Items] |
Relationship | Investor of significant influence over SFD
Shenzhen Century Communication Co., Ltd. [Member] |
Disclosure of transactions between related parties [Line Items] |
Relationship | Investor of significant influence over SCT

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- Definition Line items represent concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes of the table. + References No definition available. + Details
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Name: | dei_LegalEntityAxis=cht_SonetEntertainmentTaiwanLimitedMember
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Name: | dei_LegalEntityAxis=cht_SkysoftCoLtdMember
Namespace Prefix: |
Data Type: | na
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