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Share-based Payments Arrangement - Black-Scholes Model and Related Assumptions used to Evaluate Options and Fair Value of Options by CHPT (Detail)
Oct. 31, 2018
TWD ($)
yr
$ / shares
May 22, 2018
TWD ($)
d
$ / shares
Dec. 19, 2017
TWD ($)
yr
$ / shares
Sep. 18, 2017
TWD ($)
d
$ / shares
Oct. 22, 2015
TWD ($)
yr
$ / shares
CHIEF Telecom Inc. (CHIEF) [Member]          
Disclosure of terms and conditions of share-based payment arrangement [Line Items]          
Grant-date share price $ 166.00 $ 156.41 $ 95.92   $ 39.55
Exercise price $ 147.00 $ 170.00 $ 147.00   $ 43.00
Dividends yield 0.00% 0.00% 0.00%   0.00%
Risk-free interest rate 0.72% 0.34% 0.62%   0.86%
Expected life 5 7 5   5
Expected volatility 16.60% 14.33% 17.35%   21.02%
Weighted average fair value of grants | $ $ 33,540 $ 0 $ 2,318   $ 4,863
Chunghwa Precision Test Tech. Co., Ltd. (CHPT) [Member]          
Disclosure of terms and conditions of share-based payment arrangement [Line Items]          
Grant-date share price       $ 1,295.00  
Exercise price       $ 1,267.33  
Dividends yield       0.00%  
Risk-free interest rate       0.35%  
Expected life | d       4  
Expected volatility       28.30%  
Weighted average fair value of grants | $       $ 31.60