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Equity - Summary of Unrealized Gain (Loss) on Financial Assets at FVTOCI (Detail) - 12 months ended Dec. 31, 2018 $ in Thousands, $ in Thousands | USD ($) | TWD ($) | TWD ($)
--- | --- | --- | ---
Financial assets at fair value through other comprehensive income [line items] |  |  |
Ending balance | $ 52,183 | $ 1,597,323 |
Unrealized gain (loss) on financial assets at fair value through other comprehensive income [member] |  |  |
Financial assets at fair value through other comprehensive income [line items] |  |  |
Balance at January 1 per IAS 39 | 13,805 |  | $ 422,570
Adjustment on initial application of IFRS 9 (Note 3) | (9,377) |  | $ (287,053)
Beginning balance | 4,428 | 135,517 |
Debt instruments | (2,061) | (63,076) |
Equity instruments | (13,019) | (398,513) |
Share from associates and joint venture accounted for using the equity method | (18,140) | (555,271) |
Disposal of equity instruments and transferred cumulative gain to retained earnings | (50) | (1,518) |
Disposal of associates and joint venture accounted for using the equity method | (4,357) | (133,364) |
Share from associates and joint venture accounted for using the equity method | 36 | 1,118 |
Ending balance | $ (33,163) | $ (1,015,107) |

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