Long-Term Incentive Plans - Summary of Information Regarding Restricted Stock Unit Awards (Detail)	6 Months Ended
	Jun. 30, 2021 $ / shares shares
PRSU [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Outstanding, Number of Units, Beginning Balance | shares	0
Granted, Number of Units | shares	196,377	[1]
Forfeited, Number of Units | shares	0
Vested, Number of Units | shares	0
Outstanding, Number of Units, Ending Balance | shares	196,377
Outstanding, Weighted-Average Grant Date Fair Value per unit, Beginning balance | $ / shares	$ 0	[2]
Granted, Weighted-Average Grant Date Fair Value per Unit | $ / shares	1.94	[2]
Forfeited, Weighted-Average Grant Date Fair Value per Unit | $ / shares	0	[2]
Vested, Weighted-Average Grant Date Fair Value per Unit | $ / shares	0	[2]
Outstanding, Weighted-Average Grant Date Fair Value per unit, Ending balance | $ / shares	$ 1.94	[2]
Management Incentive Plan [Member] | TSUs [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Outstanding, Number of Units, Beginning Balance | shares	115,797
Granted, Number of Units | shares	872,588	[3]
Forfeited, Number of Units | shares	(1,244)
Vested, Number of Units | shares	(24,056)
Outstanding, Number of Units, Ending Balance | shares	963,085
Restricted Stock Units (RSUs) [Member] | TSUs [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Outstanding, Weighted-Average Grant Date Fair Value per unit, Beginning balance | $ / shares	$ 4.47	[2]
Granted, Weighted-Average Grant Date Fair Value per Unit | $ / shares	3.52	[2]
Forfeited, Weighted-Average Grant Date Fair Value per Unit | $ / shares	5.12	[2]
Vested, Weighted-Average Grant Date Fair Value per Unit | $ / shares	3.91	[2]
Outstanding, Weighted-Average Grant Date Fair Value per unit, Ending balance | $ / shares	$ 3.62	[2]
Restricted Stock Units (RSUs) [Member] | 2017 Non-Employee Directors Compensation Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Outstanding, Number of Units, Beginning Balance | shares	8,898
Granted, Number of Units | shares	0
Forfeited, Number of Units | shares	0
Vested, Number of Units | shares	(5,565)
Outstanding, Number of Units, Ending Balance | shares	3,333
Outstanding, Weighted-Average Grant Date Fair Value per unit, Beginning balance | $ / shares	$ 5.12	[2]
Granted, Weighted-Average Grant Date Fair Value per Unit | $ / shares	0	[2]
Forfeited, Weighted-Average Grant Date Fair Value per Unit | $ / shares	0	[2]
Vested, Weighted-Average Grant Date Fair Value per Unit | $ / shares	5.12	[2]
Outstanding, Weighted-Average Grant Date Fair Value per unit, Ending balance | $ / shares	$ 5.12	[2]

[1] The aggregate grant-date fair value of PRSUs issued for the six months ended June 30, 2021 was $0.4 million based on a grant-date market price ranging from $1.24 to $2.63 per share.

[2] Determined by dividing the aggregate grant-date fair value of awards by the number of awards issued.

[3] The aggregate grant-date fair value of TSUs issued for the six months ended June 30, 2021 was $3.1 million based on a grant date market price of $3.52 per share.