Income Taxes - Additional Information (Detail) - USD ($) $ in Thousands	1 Months Ended	2 Months Ended	3 Months Ended							11 Months Ended	12 Months Ended
	Feb. 09, 2018	Mar. 31, 2018	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Operating Loss Carryforwards [Line Items]
Income tax benefit	$ 18	$ (189)	$ 2,774	$ 315	$ (249)	$ 5,384	$ (455)	$ (1,694)	$ 122	$ 2,651		$ 3,357
Statutorily defined stockholders, individual ownership percentage											5.00%
Increase in stock of a corporation percentage threshold											50.00%
Aggregate testing period											3 years
Valuation allowance balance	178,303		221,913			328,661				221,913	$ 221,913	328,661	$ 346,199
Net operating loss carryforwards			16,600							16,600	16,600
Tax credit carryforwards			200							200	200
Provision to income tax expense resulting from revaluation from tax rate change	0									0		173,405
Reduction in valuation allowance resulting from revaluation from tax rate change	0									0		180,033
Unrecognized tax benefits that would affect effective tax rate if recognized			1,800			3,100				1,800	1,800	3,100
Interest and penalties expense for unrecognized tax benefits liability	$ 19									(700)		(1,500)
Accrued interest and penalties on unrecognized tax benefits liability			1,900			$ 2,500				1,900	$ 1,900	$ 2,500
Corporate federal income tax rate											21.00%	35.00%
Federal [Member]
Operating Loss Carryforwards [Line Items]
Gross operating loss carryforwards			24,700							24,700	$ 24,700
Operating loss carryforwards subject to expiration			100							100	$ 100
Federal [Member] | Minimum [Member]
Operating Loss Carryforwards [Line Items]
Expiration date											Dec. 31, 2036
Federal [Member] | Maximum [Member]
Operating Loss Carryforwards [Line Items]
Expiration date											Dec. 31, 2038
State [Member]
Operating Loss Carryforwards [Line Items]
Gross operating loss carryforwards			$ 14,500							$ 14,500	$ 14,500
State [Member] | Minimum [Member]
Operating Loss Carryforwards [Line Items]
Tax years that remain subject to examination											2012
State [Member] | Maximum [Member]
Operating Loss Carryforwards [Line Items]
Tax years that remain subject to examination											2018
IRS [Member] | Minimum [Member]
Operating Loss Carryforwards [Line Items]
Tax years that remain subject to examination											2013
IRS [Member] | Maximum [Member]
Operating Loss Carryforwards [Line Items]
Tax years that remain subject to examination											2018