Long-Term Debt - Outstanding Long-Term Debt (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Debt Instrument [Line Items]
Total long-term debt	$ 110,103	$ 118,481
Less: current maturities	(8,196)	(8,196)
Total long-term debt, net of current maturities	101,907	110,285
9.57% bond, due May 1, 2018 [Member]
Debt Instrument [Line Items]
Total long-term debt	5,444	6,348
10.03% bond, due May 1, 2018 [Member]
Debt Instrument [Line Items]
Total long-term debt	2,994	3,492
9.08% bond, due June 1, 2022 [Member]
Debt Instrument [Line Items]
Total long-term debt	7,962	7,958
7.83% note, due January 1, 2015 [Member]
Debt Instrument [Line Items]
Total long-term debt	4,000	6,000
6.64% note, due October 31, 2017 [Member]
Debt Instrument [Line Items]
Total long-term debt	13,636	16,363
5.50% note, due October 12, 2020 [Member]
Debt Instrument [Line Items]
Total long-term debt	16,000	18,000
5.93% note, due October 31, 2023 [Member]
Debt Instrument [Line Items]
Total long-term debt	30,000	30,000
5.68% note, due June 30, 2026 [Member]
Debt Instrument [Line Items]
Total long-term debt	29,000	29,000
8.25% due March 1, 2014 [Member]
Debt Instrument [Line Items]
Total long-term debt	942	1,134
Promissory note [Member]
Debt Instrument [Line Items]
Total long-term debt	$ 125	$ 186