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Financial Instruments -Recurring Basis (Details) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Mar. 31, 2014
Key inputs used in investor option liability valuation
Impairment loss for available-for-sale investments	$ 4,800,000	$ 0	$ 0
Loss on fair value change of investor option liability			(46,972,000)
Financial instruments measured on a recurring basis
Key inputs used in investor option liability valuation
Impairment loss for available-for-sale investments	$ 4,800,000	$ 0	0
Financial instruments measured on a recurring basis | Investor option liability
Key inputs used in investor option liability valuation
Investor option liability				$ 76,500,000
Loss on fair value change of investor option liability			$ (47,000,000)
Financial instruments measured on a recurring basis | Significant Unobservable Inputs (Level 3) | Alibaba
Key inputs used in investor option liability valuation
Percentage of ownership interest in subsidiary to be reached if fully exercised	30.00%

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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 gain (loss) recognized on the income statement for financial instrument classified as a liability measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(1)
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Fair value of financial instrument classified as a liability measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
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-URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19207-110258

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The amount by which the fair value of an investment in debt and equity securities categorized as Available-for-sale is less than the amortized cost basis or carrying amount of that investment at the balance sheet date and the decline in fair value is deemed to be other than temporary, before considering whether or not such amount is recognized in earnings or other comprehensive income.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=73527792&loc=d3e27161-111563

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The maximum percentage of ownership interest that can be increased to under option granted to certain shareholder.

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