Consolidated Statements of Comprehensive Income or Loss - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Statement Of Income And Comprehensive Income [Abstract]
Net (loss) income	$ (357,214)	$ (180,272)	$ 18,346
Derivative financial instruments:
Reclassification adjustment for gain included in net (loss) income	(7)	(6)	(6)
Investments in marketable securities:
Unrealized holding gain on investments	23	69
Reclassification adjustment for gain included in net (loss) income	(55)	(37)
Total other comprehensive (loss) gain	(39)	26	(6)
Comprehensive (loss) income	$ (357,253)	$ (180,246)	$ 18,340

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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Amount, after tax, of reclassification of gain (loss) from accumulated other comprehensive income (AOCI) for derivative instrument designated and qualifying as cash flow hedge included in assessment of hedge effectiveness.

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