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Borrowings - Summary of Repayment of Borrowings Including the Current Liabilities (Detail) - KRW (₩) ₩ in Millions | Dec. 31, 2018 | Dec. 31, 2017
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Disclosure of detailed information about borrowings [line items] |  |
Borrowings | ₩ 6,648,293 | ₩ 6,683,662
Debentures [member] |  |
Disclosure of detailed information about borrowings [line items] |  |
Borrowings | 5,128,649 | 4,610,453
Long-term borrowings [member] |  |
Disclosure of detailed information about borrowings [line items] |  |
Borrowings | 546,090 | 587,133
Gross carrying amount [member] |  |
Disclosure of detailed information about borrowings [line items] |  |
Borrowings | 6,668,349 |
Gross carrying amount [member] | Debentures [member] |  |
Disclosure of detailed information about borrowings [line items] |  |
Borrowings | 6,029,645 | ₩ 5,987,576
Gross carrying amount [member] | Debentures [member] | In local currency [member] |  |
Disclosure of detailed information about borrowings [line items] |  |
Borrowings | 3,790,000 |
Gross carrying amount [member] | Debentures [member] | In foreign currency [member] |  |
Disclosure of detailed information about borrowings [line items] |  |
Borrowings | 2,239,645 |
Gross carrying amount [member] | Long-term borrowings [member] |  |
Disclosure of detailed information about borrowings [line items] |  |
Borrowings | 638,704 |
Gross carrying amount [member] | Long-term borrowings [member] | In local currency [member] |  |
Disclosure of detailed information about borrowings [line items] |  |
Borrowings | 486,002 |
Gross carrying amount [member] | Long-term borrowings [member] | In foreign currency [member] |  |
Disclosure of detailed information about borrowings [line items] |  |
Borrowings | 152,702 |
Gross carrying amount [member] | Over 12 months [member] |  |
Disclosure of detailed information about borrowings [line items] |  |
Borrowings | 1,368,876 |
Gross carrying amount [member] | Over 12 months [member] | Debentures [member] |  |
Disclosure of detailed information about borrowings [line items] |  |
Borrowings | 881,335 |
Gross carrying amount [member] | Over 12 months [member] | Debentures [member] | In local currency [member] |  |
Disclosure of detailed information about borrowings [line items] |  |
Borrowings | 490,000 |
Gross carrying amount [member] | Over 12 months [member] | Debentures [member] | In foreign currency [member] |  |
Disclosure of detailed information about borrowings [line items] |  |
Borrowings | 391,335 |
Gross carrying amount [member] | Over 12 months [member] | Long-term borrowings [member] |  |
Disclosure of detailed information about borrowings [line items] |  |
Borrowings | 487,541 |
Gross carrying amount [member] | Over 12 months [member] | Long-term borrowings [member] | In local currency [member] |  |
Disclosure of detailed information about borrowings [line items] |  |
Borrowings | 436,518 |
Gross carrying amount [member] | Over 12 months [member] | Long-term borrowings [member] | In foreign currency [member] |  |
Disclosure of detailed information about borrowings [line items] |  |
Borrowings | 51,023 |
Gross carrying amount [member] | Between 1-2 years [member] |  |
Disclosure of detailed information about borrowings [line items] |  |
Borrowings | 1,076,623 |
Gross carrying amount [member] | Between 1-2 years [member] | Debentures [member] |  |
Disclosure of detailed information about borrowings [line items] |  |
Borrowings | 1,028,101 |
Gross carrying amount [member] | Between 1-2 years [member] | Debentures [member] | In local currency [member] |  |
Disclosure of detailed information about borrowings [line items] |  |
Borrowings | 460,000 |
Gross carrying amount [member] | Between 1-2 years [member] | Debentures [member] | In foreign currency [member] |  |
Disclosure of detailed information about borrowings [line items] |  |
Borrowings | 568,101 |
Gross carrying amount [member] | Between 1-2 years [member] | Long-term borrowings [member] |  |
Disclosure of detailed information about borrowings [line items] |  |
Borrowings | 48,522 |
Gross carrying amount [member] | Between 1-2 years [member] | Long-term borrowings [member] | In local currency [member] |  |
Disclosure of detailed information about borrowings [line items] |  |
Borrowings | 1,468 |
Gross carrying amount [member] | Between 1-2 years [member] | Long-term borrowings [member] | In foreign currency [member] |  |
Disclosure of detailed information about borrowings [line items] |  |
Borrowings | 47,054 |
Gross carrying amount [member] | Jan 1, 2021 ~ Dec 31, 2021 [member] |  |
Disclosure of detailed information about borrowings [line items] |  |
Borrowings | 1,311,327 |
Gross carrying amount [member] | Jan 1, 2021 ~ Dec 31, 2021 [member] | Debentures [member] |  |
Disclosure of detailed information about borrowings [line items] |  |
Borrowings | 1,222,109 |
Gross carrying amount [member] | Jan 1, 2021 ~ Dec 31, 2021 [member] | Debentures [member] | In local currency [member] |  |
Disclosure of detailed information about borrowings [line items] |  |
Borrowings | 1,060,000 |
Gross carrying amount [member] | Jan 1, 2021 ~ Dec 31, 2021 [member] | Debentures [member] | In foreign currency [member] |  |
Disclosure of detailed information about borrowings [line items] |  |
Borrowings | 162,109 |
Gross carrying amount [member] | Jan 1, 2021 ~ Dec 31, 2021 [member] | Long-term borrowings [member] |  |
Disclosure of detailed information about borrowings [line items] |  |
Borrowings | 89,218 |
Gross carrying amount [member] | Jan 1, 2021 ~ Dec 31, 2021 [member] | Long-term borrowings [member] | In local currency [member] |  |
Disclosure of detailed information about borrowings [line items] |  |
Borrowings | 45,518 |
Gross carrying amount [member] | Jan 1, 2021 ~ Dec 31, 2021 [member] | Long-term borrowings [member] | In foreign currency [member] |  |
Disclosure of detailed information about borrowings [line items] |  |
Borrowings | 43,700 |
Gross carrying amount [member] | Jan 1, 2022 ~ Dec 31, 2022 [member] |  |
Disclosure of detailed information about borrowings [line items] |  |
Borrowings | 458,683 |
Gross carrying amount [member] | Jan 1, 2022 ~ Dec 31, 2022 [member] | Debentures [member] |  |
Disclosure of detailed information about borrowings [line items] |  |
Borrowings | 447,240 |
Gross carrying amount [member] | Jan 1, 2022 ~ Dec 31, 2022 [member] | Debentures [member] | In foreign currency [member] |  |
Disclosure of detailed information about borrowings [line items] |  |
Borrowings | 447,240 |
Gross carrying amount [member] | Jan 1, 2022 ~ Dec 31, 2022 [member] | Long-term borrowings [member] |  |
Disclosure of detailed information about borrowings [line items] |  |
Borrowings | 11,443 |
Gross carrying amount [member] | Jan 1, 2022 ~ Dec 31, 2022 [member] | Long-term borrowings [member] | In local currency [member] |  |
Disclosure of detailed information about borrowings [line items] |  |
Borrowings | 518 |
Gross carrying amount [member] | Jan 1, 2022 ~ Dec 31, 2022 [member] | Long-term borrowings [member] | In foreign currency [member] |  |
Disclosure of detailed information about borrowings [line items] |  |
Borrowings | 10,925 |
Gross carrying amount [member] | More than 5 years [member] |  |
Disclosure of detailed information about borrowings [line items] |  |
Borrowings | 2,452,840 |
Gross carrying amount [member] | More than 5 years [member] | Debentures [member] |  |
Disclosure of detailed information about borrowings [line items] |  |
Borrowings | 2,450,860 |
Gross carrying amount [member] | More than 5 years [member] | Debentures [member] | In local currency [member] |  |
Disclosure of detailed information about borrowings [line items] |  |
Borrowings | 1,780,000 |
Gross carrying amount [member] | More than 5 years [member] | Debentures [member] | In foreign currency [member] |  |
Disclosure of detailed information about borrowings [line items] |  |
Borrowings | 670,860 |
Gross carrying amount [member] | More than 5 years [member] | Long-term borrowings [member] |  |
Disclosure of detailed information about borrowings [line items] |  |
Borrowings | 1,980 |
Gross carrying amount [member] | More than 5 years [member] | Long-term borrowings [member] | In local currency [member] |  |
Disclosure of detailed information about borrowings [line items] |  |
Borrowings | ₩ 1,980 |

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