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Disposal of Subsidiaries - Summary of Gain on Disposal of Subsidiaries (Detail) - TWD ($) $ in Thousands | 1 Months Ended | 12 Months Ended
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Jun. 30, 2017 | Dec. 31, 2017
Disclosure of gain from disposals of subsidiaries [line items] |  |
Total consideration |  | $ 7,046,464
Cash and cash equivalents | $ 29,133 |
Inventories related to real estate business | 1,427,874 |
Net assets disposed of | 1,457,007 |
Kun Shan Ding Yue Real Estate Development Co., Ltd. [member] |  |
Disclosure of gain from disposals of subsidiaries [line items] |  |
Total consideration | 7,046,464 |
Net assets disposed of | (1,457,007) |
Gain on disposal of KSDY | $ 5,589,457 |

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