Income Taxes - Reconciliation of Actual Income Tax Expense (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Income tax (expense) benefit at the federal statutory rate	$ (25,840)	$ 48,869	$ 59,632
State income taxes, net of federal tax effect	(5,144)	4,030	4,971
Change in federal tax rate	0	(64,949)	0
Refundable AMT credits	0	(1,402)	0
Nondeductible equity-based compensation	3,101	13,655	64
Nondeductible costs in connection with Merger	(2,545)	0	0
Other permanent items	(418)	(37)	(62)
Change in valuation allowance	36,321	(35,684)	(64,477)
Change in valuation allowance due to TCJA	0	64,949	0
Change in valuation allowance - Section 382	64,994	0	0
Change in apportioned state tax rates	723	1,086	0
Eliminate UT jurisdiction NOL's and credits	0	(2,647)	0
Change in ownership - Section 382	(64,994)	0	0
Other, net	(377)	210	0
Income tax (expense) benefit	$ (1,827)	$ 1,402	$ 0