Income Taxes - Components of Net Deferred Income Tax Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Deferred income tax assets:
Property, Plant & Equipment	$ 115,695	$ 37,075
Net operating loss carryforward	174,479	141,534
Derivatives	2,448	0
Disallowed interest expense	5,388	10,627
Accrued liabilities	1,226	1,431
Other	1,717	4,234
Total deferred income tax assets:	300,953	194,901
Valuation allowance	(300,386)	(189,941)
Net deferred income tax assets	567	4,960
Deferred income tax liabilities:
Derivatives	0	2,767
Other	567	2,193
Total deferred income tax liabilities	567	4,960
Net deferred income tax liabilities	$ 0	$ 0

Deferred tax assets disallowed interest expense.

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Deferred tax assets other noncurrent.

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Amount of deferred tax liability attributable to taxable temporary differences.

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Amount of deferred tax assets for which it is more likely than not that a tax benefit will not be realized.

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