Other Non-Current Liabilities - Summary of Other Non-Current Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Liabilities, Noncurrent [Abstract]
Retirement benefits	$ 6,073	$ 8,940
Derivative instruments	2,504	29
Unrecognized tax benefits	907	907
Deferred transition revenue	509	924
Finance lease liabilities	254	281
Accrued capital expenditures	0	3,486
Others	3,282	3,568
Other non-current liabilities	$ 13,529	$ 18,135
Finance Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]	Other non-current liabilities	Other non-current liabilities

Capital Expenditure, Liability, Noncurrent

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- Definition

Amount of obligation to transfer good or service to customer for which consideration has been received or is receivable, classified as noncurrent.

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Fair value of liability arising from contracts that meet the criteria of being accounted for as derivative instruments, financial instrument or contract used to mitigate a specified risk (hedge), energy marketing activities (trading activities), expected to be settled after one year or beyond the normal operating cycle, if longer. Examples of energy marketing activities include, but are not limited to, trading of electricity, coal, natural gas and oil using financial instruments, including, but not limited to, forward contracts, options and swaps.

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Present value of lessee's discounted obligation for lease payments from finance lease, classified as noncurrent.

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Indicates line item in statement of financial position that includes noncurrent finance lease liability.

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Amount recognized for uncertainty in income taxes classified as noncurrent.

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Amount of liabilities classified as other, due after one year or the normal operating cycle, if longer.

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- Definition

Obligations not otherwise itemized or categorized in the footnotes to the financial statements that are expected to be paid after one year (or the normal operating cycle, if longer), from the balance sheet date.

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- Definition

Amount of liability, recognized in statement of financial position, for defined benefit pension and other postretirement plans, classified as noncurrent.

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