Long-Term Debt - Outstanding Long-Term Debt (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Debt Instrument [Line Items]
Long-term Debt	$ 145,900	$ 153,700
Capital lease obligation	3,471	4,824
Less: debt issuance costs	(291)	(333)
Long-term Debt and Capital Lease Obligations	149,053	158,157
Less: current maturities	(12,099)	(9,151)
Total long-term debt, net of current maturities	136,954	149,006
9.08% bond, due June 1, 2022
Debt Instrument [Line Items]
Long-term Debt	7,978	7,973
6.64% note, due October 31, 2017
Debt Instrument [Line Items]
Long-term Debt	2,727	5,455
5.50% note, due October 12, 2020
Debt Instrument [Line Items]
Long-term Debt	8,000	10,000
5.93% note, due October 31, 2023
Debt Instrument [Line Items]
Long-term Debt	21,000	24,000
5.68% note, due June 30, 2026
Debt Instrument [Line Items]
Long-term Debt	29,000	29,000
6.43% note, due May 2, 2028
Debt Instrument [Line Items]
Long-term Debt	7,000	7,000
3.73% note, due December 16, 2028
Debt Instrument [Line Items]
Long-term Debt	20,000	20,000
3.88% note, due May 15, 2029
Debt Instrument [Line Items]
Long-term Debt	50,000	50,000
Promissory note
Debt Instrument [Line Items]
Long-term Debt	$ 168	$ 238