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Income Taxes - Tax Effects of Significant Temporary Differences Representing Net Deferred Tax Asset and Liability (Detail) - USD ($)
$ in Thousands
Dec. 31, 2020
Dec. 31, 2019
Deferred tax assets:    
Asset retirement obligation $ 4,061 $ 3,812
Net operating loss carryforwards 59,335 51,656
Interest expense limitation 55,026 62,552
Unrealized hedging losses 10,452 0
Other 5,661 9,022
Noncurrent deferred tax assets 134,535 127,042
Valuation allowance on deferred tax assets (15,964) (16,876)
Deferred tax assets 118,571 110,166
Deferred tax liabilities:    
Property and equipment (283,959) (269,587)
Unrealized hedging income 0 (10,763)
Bond discount (30,591) (37,458)
Other (4,604) (4,130)
Deferred tax liabilities (319,154) (321,938)
Net deferred tax liability $ (200,583) $ (211,772)