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The amount of net income or loss for the period per each share in instances when basic and diluted earnings per share are the same amount and reported as a single line item on the face of the financial statements. Basic earnings per share is the amount of net income or loss for the period per each share of common stock or unit outstanding during the reporting period. Diluted earnings per share includes the amount of net income or loss for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

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Additional shares included in the calculation of diluted EPS as a result of the potentially dilutive effect of share based payment arrangements using the treasury stock method.

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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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The average number of shares or units issued and outstanding that are used in calculating diluted EPS or earnings per unit (EPU), determined based on the timing of issuance of shares or units in the period.

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Summary of Significant Accounting Policies - Net Loss Per Common Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Numerator:
Net loss	$ (91,573)	$ (87,743)	$ (76,437)	$ (68,524)	$ (65,384)	$ (45,179)	$ (44,672)	$ (37,414)	$ (324,277)	$ (192,649)	$ (176,273)
Denominator:
Weighted average common shares used in calculation of basic net loss per share (in shares)									76,889	66,576	61,892
Effect of dilutive securities:
Weighted average common shares outstanding used in calculation of diluted net loss per share (in shares)									76,889	66,576	61,892
Net loss per share:
Basic and diluted (in dollars per share)	$ (1.19)	$ (1.14)	$ (1.00)	$ (0.89)	$ (0.85)	$ (0.69)	$ (0.72)	$ (0.60)	$ (4.22)	$ (2.89)	$ (2.85)
Common stock options
Effect of dilutive securities:
Dilutive securities (in shares)									0	0	0
Restricted stock and restricted stock units
Effect of dilutive securities:
Dilutive securities (in shares)									0	0	0