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American Depositary Shares, Premium Percentage

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American Depositary Shares Purchased, Price Per Share

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American Depository Shares, Conversion Ratio

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Debt Instrument, Convertible, Deferred Finance Cost Allocated to Liability Component

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Debt Instrument, Convertible, Scheduled Threshold Trading Days

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Debt Instrument, Convertible, Threshold Consecutive Business Days

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Debt Instrument, Option to Increase Face Amount

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Remaining amortization period for discount on the liability component of convertible debt which may be settled in cash upon conversion, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Threshold period of specified consecutive trading days within which common stock price to conversion price of convertible debt instrument must exceed threshold percentage for specified number of trading days to trigger conversion feature.

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Minimum percentage of common stock price to conversion price of convertible debt instruments to determine eligibility of conversion.

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Threshold number of specified trading days that common stock price to conversion price of convertible debt instruments must exceed threshold percentage within a specified consecutive trading period to trigger conversion feature.

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

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Contractual interest rate for funds borrowed, under the debt agreement.

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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, after accumulated amortization, of debt issuance costs. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.

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Amount of long-term debt classified as other.

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The cash inflow from a debt initially having maturity due after one year or beyond the operating cycle, if longer.

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Long-Term Debt (Details)		9 Months Ended
Long-Term Debt (Details)	Feb. 16, 2018 USD ($)	Sep. 30, 2018 USD ($) day $ / shares	Sep. 30, 2017 USD ($)	Dec. 31, 2017 USD ($)
Debt Instrument [Line Items]
Net proceeds from the note		$ 143,750,000	$ 0
ADS, option price per share (in dollars per share) \| $ / shares		$ 10.79
ADS, premium percentage		20.00%
ADS purchased, price per share (in dollars per share) \| $ / shares		$ 8.99
Other debt		$ 721,000		$ 191,000
Debt Instrument, Redemption, Period One
Debt Instrument [Line Items]
Consecutive business days		5 days
Consecutive trading days \| day		5
Debt Instrument, Redemption, Period Two
Debt Instrument [Line Items]
Scheduled threshold trading days		95 days
Threshold trading days \| day		35
Debt Instrument, Redemption, Period Three
Debt Instrument [Line Items]
Consecutive trading days \| day		30
Threshold trading days \| day		20
Threshold percentage of stock price trigger		130.00%
4.50% Exchangeable Senior Notes Due 2023
Debt Instrument [Line Items]
Debt instrument, face amount	$ 125,000,000
Debt instrument, interest rate, stated percentage	4.50%	4.50%
Option to increase aggregate principal amount	$ 18,750,000
Net proceeds from the note	$ 137,560,000
ADS, conversion ratio		92.6956
Convertible Debt
Debt Instrument [Line Items]
Remaining discount amortization period		5 years
Convertible Debt \| 4.50% Exchangeable Senior Notes Due 2023
Debt Instrument [Line Items]
Debt discount and issuance costs, net		$ 6,190,000
Debt issuance cost allocated to equity component		1,201,000
Debt issuance cost allocated to liability component		4,989,000
Loans Payable
Debt Instrument [Line Items]
Other debt		$ 226,000		$ 267,000