Income Taxes - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards, State	$ 3,170,000
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount	300	$ 400	$ 1,000
Deferred Tax Assets, Valuation Allowance	19,633	$ 19,341
UNITED STATES
Operating Loss Carryforwards [Line Items]
Federal Operating Loss Carryforwards	1,950,000
OKLAHOMA
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards, State	2,140,000
NORTH DAKOTA
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards, State	$ 900,000