Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement Of Income And Comprehensive Income [Abstract]
Net loss	$ (96,692)	$ (153,524)	$ (81,177)
Other comprehensive income (loss):
Net unrealized gain (loss) on available-for-sale investments, net of tax	(533)	79	(226)
Net foreign currency translation gain (loss)	785	(272)	(377)
Other comprehensive income (loss), net of tax	252	(193)	(603)
Comprehensive loss	$ (96,440)	$ (153,717)	$ (81,780)

The change in unrealized holding gain (loss), net of tax, on available-for-sale securities included in a separate component of shareholders' equity during the period.

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Amount after tax of increase (decrease) in equity from transactions and other events and circumstances from net income and other comprehensive income, attributable to parent entity. Excludes changes in equity resulting from investments by owners and distributions to owners.

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The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

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Amount after tax and reclassification adjustments of gain (loss) on foreign currency translation adjustments, foreign currency transactions designated and effective as economic hedges of a net investment in a foreign entity and intra-entity foreign currency transactions that are of a long-term-investment nature.

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Amount after tax and reclassification adjustments of other comprehensive income (loss).

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