American Depositary Shares, Option Price Per Share

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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, Scheduled Threshold Trading Days

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Debt Instrument, Convertible, Threshold Consecutive Business Days

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- Definition

Debt Instrument, Option to Increase Face Amount

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Adjustment to additional paid in capital resulting from the recognition of convertible debt instruments as two separate components - a debt component and an equity component. This bifurcation may result in a basis difference associated with the liability component that represents a temporary difference for purposes of applying accounting for income taxes. The initial recognition of deferred taxes for the tax effect of that temporary difference is as an adjustment to additional paid in capital.

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-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 25
-Paragraph 22
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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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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 instruments must exceed threshold percentage for a specified number of trading days to trigger conversion feature, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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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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- Definition

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 of unamortized debt discount (premium) and debt issuance costs.

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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)		3 Months Ended
Long-Term Debt (Details)	Feb. 16, 2018 USD ($)	Mar. 31, 2018 USD ($) day $ / shares	Mar. 31, 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
Adjustments to additional paid in capital, equity component of convertible debt		$ 26,699,000
Remaining discount amortization period		5 years
Debt Instrument, Redemption, Period One [Member]
Debt Instrument [Line Items]
Consecutive business days		5 days
Consecutive trading days		5 days
Debt Instrument, Redemption, Period Two [Member]
Debt Instrument [Line Items]
Scheduled threshold trading days		95 days
Threshold trading days \| day		35
Debt Instrument, Redemption, Period Three [Member]
Debt Instrument [Line Items]
Consecutive trading days		30 days
Threshold trading days \| day		20
Threshold percentage of stock price trigger		130.00%
4.50% Exchangeable Senior Notes Due 2023 [Member]
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
Debt discount and issuance costs, net		$ 6,190,000
Additional Paid-in Capital \| 4.50% Exchangeable Senior Notes Due 2023 [Member]
Debt Instrument [Line Items]
Adjustments to additional paid in capital, equity component of convertible debt		1,201,000
Assets [Member] \| 4.50% Exchangeable Senior Notes Due 2023 [Member]
Debt Instrument [Line Items]
Adjustments to additional paid in capital, equity component of convertible debt		4,989,000
Other Long-Term Debt [Member]
Debt Instrument [Line Items]
Long-term debt		$ 320,000		$ 267,000