Coupon Interest Payable Quarterly.

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Coupon Interest Payable Quarterly Percentage.

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Coupon Yield To Maturity Return.

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Coupon Yield To Maturity Return Percentage.

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Debt Instrument Year Of Maturity

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Forfeiture Of Unpaid Yield To Maturity Interest.

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Long Term Debt Default Rate Of Interest.

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Payment Of Accrued Coupon Interest.

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Percentage of shares issuable in initial public offer.

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Stock Shares Issued During The Period Warrant Excercises.

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The amount of subsequent adjustments to additional paid in capital for convertible financial instruments where a component of equity and a component of debt are recognized.

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Date the warrants or rights are exercisable, in CCYY-MM-DD format.

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Number of securities into which the class of warrant or right may be converted. For example, but not limited to, 500,000 warrants may be converted into 1,000,000 shares.

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The value of the financial instrument(s) that the original debt is being converted into in a noncash (or part noncash) transaction. "Part noncash" refers to that portion of the transaction not resulting in cash receipts or cash payments in the period.

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The number of shares issued in exchange for the original debt being converted in a noncash (or part noncash) transaction. "Part noncash" refers to that portion of the transaction not resulting in cash receipts or payments in the period.

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The price per share of the conversion feature embedded in the debt instrument.

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The number of equity instruments that the holder of the debt instrument would receive if the debt was converted to equity.

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Face (par) amount of debt instrument at time of issuance.

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Description of the interest rate as being fixed or variable, and, if variable, identification of the index or rate on which the interest rate is based and the number of points or percentage added to that index or rate to set the rate, and other pertinent information, such as frequency of rate resets.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Amount of the required periodic payments applied to principal.

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Rate since inception resulting in zero net present value of cash flows from investment.

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Maturity date of long-term debt, in CCYY-MM-DD format.

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The interest rate applicable to the portion of the carrying amount of long-term borrowings outstanding as of the balance sheet date, including current maturities, which accrues interest at a set, unchanging rate.

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The cash inflow from a borrowing with the highest claim on the assets of the entity in case of bankruptcy or liquidation (with maturities initially due after one year or beyond the operating cycle, if longer).

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Identify the stated interest rate per the agreement, for example, leasing and debt arrangements between related parties.

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The cash outflow for the payment of a long-term borrowing made from a related party where one party can exercise control or significant influence over another party; including affiliates, owners or officers and their immediate families, pension trusts, and so forth. Alternate caption: Payments for Advances from Affiliates.

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Expiration date of outstanding warrant and right embodying unconditional obligation requiring redemption by transferring asset at specified or determinable date or upon event certain to occur, in CCYY-MM-DD format.

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Debt - Additional Information (Detail) ₩ / shares in Units, $ / shares in Units, $ in Thousands, ₩ in Billions				1 Months Ended								2 Months Ended	3 Months Ended	12 Months Ended
	May 15, 2020 USD ($) shares	May 15, 2020 KRW (₩) shares	Aug. 01, 2019	Sep. 30, 2020 USD ($)	Sep. 30, 2020 KRW (₩)	Jun. 30, 2020 USD ($)	Jun. 30, 2020 KRW (₩)	Aug. 31, 2019 USD ($)	Aug. 31, 2019 KRW (₩)	May 31, 2019 USD ($)	May 31, 2019 KRW (₩)	Jun. 30, 2020 USD ($) shares	Mar. 31, 2021	Dec. 31, 2020 USD ($)	Dec. 31, 2017 USD ($) $ / shares shares	Dec. 31, 2020 ₩ / shares	Jan. 01, 2020 USD ($)	Jan. 01, 2020 KRW (₩)	May 31, 2019 KRW (₩)	Dec. 31, 2017 KRW (₩) ₩ / shares shares	May 31, 2017 USD ($) shares	May 31, 2017 KRW (₩) ₩ / shares shares
Debt Instrument [Line Items]
Repayment of related party debt														$ 42,371
Debt instrument converted into equity amount stock value														$ 187,095
Stic [Member]
Debt Instrument [Line Items]
Internal rate of return percentage															8.00%
Percentage of shares issuable in initial public offer															50.00%					50.00%
2.5% Convertible bonds due 2024 [Member] \| Stic [Member]
Debt Instrument [Line Items]
Debt instrument face amount															$ 185,000					₩ 210.0
Convertible bonds long term rate of interest															2.50%					2.50%
Debt instrument year of maturity															2024
Debt instrument conversion price per share \| ₩ / shares																₩ 293,600				₩ 293,600
Debt instrument number of shares issuable on conversion															715,258
Debt instrument shares issued on conversion \| shares												715,258
Coupon interest payable						$ 900						$ 900
Coupon yield to maturity return						4,500						$ 4,500
Debt instrument converted into equity amount	$ 187,100	₩ 229.7
Debt instrument converted into equity amount stock value	5,800	7.2
Debt instrument converted into equity amount recorded in additional paid in capital	181,300	222.5
2.5% Convertible bonds due 2024 [Member] \| Stic [Member] \| Previously Reported [Member]
Debt Instrument [Line Items]
Debt instrument face amount															$ 193,000
2.5% Non convertible bonds due 2024 [Member] \| Stic [Member]
Debt Instrument [Line Items]
Debt instrument face amount															$ 79,000					₩ 90.0	$ 83,000	₩ 90.0
Convertible bonds long term rate of interest															2.50%					2.50%
Debt instrument year of maturity															2024
Class of warrants or rights number of shares covered by the warrants or rights \| shares															306,540					306,540	306,539	306,539
Class of warrants or rights conversion price per share \| (per share)															$ 270					₩ 293,600		₩ 293,600
Long term debt instrument maturity date															May 26, 2024					May 26, 2024
Coupon interest payable quarterly percentage														5.00%	0.625%
Coupon yield to maturity return percentage														5.00%
Long term debt default rate of interest														9.00%
Debt instrument converted into equity amount	64,400	79.0
Debt instrument converted into equity amount stock value	2,500	3.1
Debt instrument converted into equity amount recorded in additional paid in capital	$ 61,900	₩ 75.9
Class of warrants of rights the date from which the rights are excercisable														May 25, 2018
Class of warrants or rights maturity date																Apr. 26, 2024
Stock shares issued during the period warrant excercises \| shares	306,539	306,539
Payment of accrued coupon interest	$ 300
Forefeiture of unpaid yield to maturity interest	$ 1,900
2.5% Non convertible bonds due 2024 [Member] \| Stic [Member] \| Possible Premature Redemption [Member]
Debt Instrument [Line Items]
Long term debt instrument maturity date															May 26, 2022					May 26, 2022
2.5% Non convertible bonds due 2024 [Member] \| Stic [Member] \| Previously Reported [Member]
Debt Instrument [Line Items]
Debt instrument face amount															$ 83,000
Class of warrants or rights number of shares covered by the warrants or rights \| shares															306,539					306,539
3.5% senior notes due in 2020 [Member]
Debt Instrument [Line Items]
Debt instrument face amount										$ 74,000									₩ 80.0
Convertible bonds long term rate of interest										3.50%									3.50%
Debt instrument year of maturity			2020
Debt instrument periodic payment principal								$ 18,000	₩ 20.0
Debt instrument terms of interest payment			Quarterly interest
4.3% senior note [Member]
Debt Instrument [Line Items]
Convertible bonds long term rate of interest										4.30%									4.30%
Proceeds from senior notes										$ 18,000	₩ 20.0
4.6% senior notes due to related parties in 2024 [Member]
Debt Instrument [Line Items]
Debt instrument face amount																	$ 92,000	₩ 100.0
Related party transaction rate of interest													4.60%	4.60%
Long term debt instrument maturity date																	May 27, 2024	May 27, 2024
4.6% senior notes due to related parties in 2024 [Member] \| Principal [Member]
Debt Instrument [Line Items]
Repayment of related party debt				$ 18,000	₩ 20.0	28,000	₩ 30.0
4.6% senior notes due to related parties in 2024 [Member] \| Interest [Member]
Debt Instrument [Line Items]
Repayment of related party debt				$ 1,000	₩ 1.2	$ 2,600	₩ 3.1