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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, 2016
Dec. 31, 2015
Deferred tax assets:    
Property and equipment $ 15,164 $ 58,993
Net operating loss carryforwards 339,914 255,571
Alternative minimum tax carryforward 20,435 20,435
Unrealized hedging loss 2,110  
Gain on debt exchange 20,194  
Other 8,523 7,895
Noncurrent deferred tax assets 406,340 342,894
Valuation allowance on deferred tax assets (398,120) (330,372)
Deferred tax assets 8,220 12,522
Deferred tax liabilities:    
Property and equipment (9,203) (9,047)
Unrealized hedging income   (506)
Original issue discount (4,025)  
Other (4,118) (4,934)
Deferred tax liabilities (17,346) (14,487)
Net deferred tax liability $ (9,126) $ (1,965)