Debt - Additional Information (Detail) - USD ($)		12 Months Ended
	Jul. 14, 2017	Dec. 31, 2018	Dec. 31, 2019	Jul. 13, 2017
Line of Credit Facility [Line Items]
Revolving credit borrowing		$ 132,300,000	$ 131,300,000
Letters of credit outstanding		3,300,000	3,200,000
Financing lease obligations		4,900,000	4,200,000
Other obligations		1,700,000	1,300,000
Long-term debt, Fair value		$ 134,000,000	133,000,000
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
Finance Lease [Member]
Line of Credit Facility [Line Items]
Weighted average interest rate		5.01%	5.42%
Other Obligations [Member]
Line of Credit Facility [Line Items]
Weighted average interest rate		6.11%	6.11%
Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Line of credit facility, expiration date	Jul. 14, 2022
Amortization period on real estate component of borrowing base	12 years 6 months
Revolving credit borrowing		$ 132,300,000	$ 131,300,000
Weighted average interest rate		4.27%	3.35%
Additional committed borrowing capacity		$ 31,500,000	$ 31,500,000
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			$ 160,000,000
Line of credit facility, conditional maximum borrowing capacity	300,000,000
Uncommitted conditional increased borrowing capacity during period	$ 50,000,000