Long-Term Debt - Summary of Weighted-Average Interest Rates Paid Excluding Commitment Fees on Variable-Rate Debt Obligations (Detail)	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
New Revolving Credit Facility [Member]
Line Of Credit Facility [Line Items]
Revolving credit facility, weighted-average interest rates	4.89%		4.99%
Emergence Credit Facility [Member]
Line Of Credit Facility [Line Items]
Revolving credit facility, weighted-average interest rates		5.94%		5.73%