Debt - Additional Information (Detail) - USD ($)		9 Months Ended
	Jul. 14, 2017	Sep. 30, 2019	Dec. 31, 2018	Sep. 30, 2018
Line of Credit Facility [Line Items]
Revolving credit borrowing		$ 147,800,000	$ 132,300,000	$ 163,600,000
Letters of credit outstanding		3,300,000
Other obligations		1,400,000
Financing lease obligations		4,300,000
Minimum [Member]
Line of Credit Facility [Line Items]
Fall of excess borrowing availability		17,500,000
Maximum [Member]
Line of Credit Facility [Line Items]
Fall of excess borrowing availability		$ 31,300,000
Other Obligations [Member]
Line of Credit Facility [Line Items]
Debt instrument maturity year		2023
Debt instrument interest rate		6.11%
Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Line of credit facility, due and payable date	Jul. 14, 2022
Amortization period on real estate component of borrowing base	12 years 6 months
Revolving credit borrowing		$ 147,800,000
Weighted average interest rate		3.87%
Excess committed borrowing availability		$ 43,600,000
Unused commitment fees		0.25%
Fixed charge coverage ratio of credit facility		100.00%
Revolving Credit Facility [Member] | Asset Backed Securities [Member]
Line of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity	$ 250,000,000