Bank Credit Agreements and Other Short-Term and Long-Term Debt - Schedule of Debt (Parenthetical) (Details) - Notes Payable to Bank $ in Millions	12 Months Ended
Dec. 31, 2018 TWD ($)
Taiwan Bank
Debt Instrument [Line Items]
Long-term Debt, Gross	$ 140
Long-term fixed interest rate	1.30%
Debt Instrument, maturity date, description	TWD 140 million, fixed interest rate of 1.3%, matures June 28, 2033.
Debt instrument, maturity date	Jun. 28, 2033
Yuan Ta Bank
Debt Instrument [Line Items]
Long-term Debt, Gross	$ 113
Long-term fixed interest rate	1.70%
Debt Instrument, maturity date, description	TWD 113 million, fixed interest rate of 1.7%, matures on January 29, 2019.
Debt instrument, maturity date	Jan. 29, 2019

Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

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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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Date when the debt instrument is scheduled to be fully repaid, in CCYY-MM-DD format.

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Description of the maturity date of the debt instrument including whether the debt matures serially and, if so, a brief description of the serial maturities.

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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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