XML 207 R191.htm IDEA: XBRL DOCUMENT v3.8.0.1
Financial Instruments - Additional Information (Detail)
$ in Thousands, $ in Thousands
 12 Months Ended
Dec. 31, 2017
TWD ($)
Dec. 31, 2017
USD ($)
Dec. 31, 2016
TWD ($)
Dec. 31, 2015
TWD ($)
Dec. 31, 2017
USD ($)
Disclosure of detailed information about financial instruments [line items]          
Transfers between levels $ 0   $ 0    
Impairment loss $ (714,675) $ (24,112) $ (888,231) $ (258,129)  
Floating interest rate [member]          
Disclosure of detailed information about financial instruments [line items]          
Increase decrease in basis points 1.00% 1.00% 1.00% 1.00%  
Increase decrease in profit before tax $ 24,000 $ 810 $ 358,000 $ 117,000  
Currency risk [member]          
Disclosure of detailed information about financial instruments [line items]          
Value at risk 101,000   69,000 18,000 $ 3,408
Other price risk [member]          
Disclosure of detailed information about financial instruments [line items]          
Increase decrease in profit before tax $ 52,000 $ 1,754 26,000 7,100  
Equity debt ratio 1.00% 1.00%      
Increase decrease in other comprehensive income $ 13,000 $ 439 13,000 10,000  
Decrease in profit before income tax     510,000 605,000  
Increase in profit before income tax     445,000 $ 638,000  
Other Gains and Losses Net [member]          
Disclosure of detailed information about financial instruments [line items]          
Impairment loss $ 50,206 $ 1,694 $ 90,000