Annual report pursuant to Section 13 and 15(d)

INVESTMENTS (Details 1)

v3.21.1
INVESTMENTS (Details 1)
₩ / shares in Units, ₩ in Billions
 12 Months Ended
Sep. 28, 2020
KRW (₩)
₩ / shares
Dec. 31, 2020
$ / shares
Dec. 31, 2020
KRW (₩)
₩ / shares
Jun. 29, 2020
$ / shares
Feb. 21, 2020
$ / shares
Dec. 31, 2019
$ / shares
Jun. 19, 2019
$ / shares
Schedule Of Investments [Line Items]              
Stock price       $ 1.67     $ 10.30
Conversion price   $ 10.00          
Valuation Technique Binomial Monte-Carlo Cliquet Option Pricing Model [Member]              
Schedule Of Investments [Line Items]              
Principal outstanding (South Korean won) | ₩ ₩ 30   ₩ 30        
Stock price   1.23     $ 1.89 $ 1.97  
Conversion price   $ 2.00     $ 3.00 $ 9.52  
Valuation Technique Binomial Monte-Carlo Cliquet Option Pricing Model [Member] | Expected Life (in years) [Member]              
Schedule Of Investments [Line Items]              
Expected life (in years) 10 years 9 years 9 months 14 days          
Valuation Technique Binomial Monte-Carlo Cliquet Option Pricing Model [Member] | Selected Yield [Member]              
Schedule Of Investments [Line Items]              
Investment in convertible bonds, measurement input 13.00   10.50        
Valuation Technique Binomial Monte-Carlo Cliquet Option Pricing Model [Member] | Expected Volatility (Telcon common stock) [Member]              
Schedule Of Investments [Line Items]              
Investment in convertible bonds, measurement input 86.90   85.80        
Valuation Technique Binomial Monte-Carlo Cliquet Option Pricing Model [Member] | Risk-free Interest Rate (South Korea government bond) [Member]              
Schedule Of Investments [Line Items]              
Investment in convertible bonds, measurement input 1.50   1.72        
Valuation Technique Binomial Monte-Carlo Cliquet Option Pricing Model [Member] | Expected Dividend Yield [Member]              
Schedule Of Investments [Line Items]              
Investment in convertible bonds, measurement input 0.00   0.00        
Valuation Technique Binomial Monte-Carlo Cliquet Option Pricing Model [Member] | Conversion Price [Member]              
Schedule Of Investments [Line Items]              
Conversion price | ₩ / shares ₩ 9,232   ₩ 6,028