Summary of Significant Accounting Policies - Additional Information 3 (Detail) - USD ($)	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2017	Dec. 31, 2018
Operations And Summary Of Significant Accounting Policies [Line Items]
Federal statutory rate	21.00%		21.00%
Operating losses carryforward indefinitely with no carryback as percentage of taxable income			80.00%
Interest expense threshold percentage of adjusted taxable income beyond which interest expense is deductible			30.00%
Refundable unused AMT credit carryforward, Percentage			50.00%
Refundable unused alternative minimum tax credit carryforward years			2018 through 2020
Unused AMT credit carryforwards	$ 20,400,000		$ 20,400,000
Net operating loss limitation			$ 3,300,000
Period of increase in net operating loss limitation			5 years
Section 382 limitation recognition period			2018 to 2023
Net operating loss expiration period			20 years
Derivative financial instruments, asset	15,153,000		$ 15,153,000
Derivative financial instruments, current asset	14,284,000		14,284,000			$ 15,401,000
Derivative financial instruments, long-term asset	869,000		869,000
Long Term Debt
Operations And Summary Of Significant Accounting Policies [Line Items]
Long-term debt, including current portion, Carrying Value	818,500,000		818,500,000
Level 2 | Long Term Debt
Operations And Summary Of Significant Accounting Policies [Line Items]
Long-term debt, including current portion, Fair Value	652,400,000		652,400,000
Fair Value, Measurements, Recurring | Level 3
Operations And Summary Of Significant Accounting Policies [Line Items]
Financial assets	0		0
Financial liabilities	$ 0		$ 0
Predecessor
Operations And Summary Of Significant Accounting Policies [Line Items]
Federal statutory rate		21.00%		21.00%	35.00%