Long-Term Bank Debt - Additional Information (Detail) (USD $)	6 Months Ended				6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014 Equipment Loan [Member]	Jul. 31, 2013 Equipment Loan [Member]	Jun. 30, 2014 Minimum [Member]	Jun. 30, 2014 Maximum [Member]	Jun. 30, 2014 Interest Rate Swap [Member]
Debt Instrument [Line Items]
Credit facility borrowing capacity	$ 250,000,000
Maturity date of amended and restated credit agreement	Jul. 30, 2017
Credit facility borrowing base	160,000,000
Credit facility, interest rate description	The Company's borrowing rates in the credit facility provide for base rate loans at the prime rate (3.25% at June 30, 2014) plus applicable margin utilization rates that range from 1.50% to 2.00%, and LIBO rate loans at LIBO published rates plus applicable utilization rates (2.50% to 3.00% at June 30, 2014). At June 30, 2014, the Company had in place one base rate loan and one LIBO rate loan with effective rates of 4.75% and 2.65%, respectively.
Percentage for base rate loans at the prime rate	3.25%		3.95%				0.563%
Minimum range for applicable margin utilization rate	1.50%
Maximum range for applicable margin utilization rate	2.00%
Debt instrument interest one base rate basis for effective rate	4.75%
LIBOR rate loans					2.50%	3.00%
Effective LIBOR loan rate	2.65%
Outstanding borrowings under revolving credit facility	102,800,000
Weighted-average interest rate of borrowings	3.59%
Credit facility remaining borrowing capacity	57,200,000
Debt instrument basis weighted average interest rate spread on variable rate	3.53%	3.57%
Equipment Loan, face amount				10,000,000
Equipment Loan, monthly payment			184,000
Equipment Loan, maturity date			Jul. 31, 2018
Company's bank debt			8,500,000				75,000,000
Interest swap agreements period							2 years
Commenced date							Jan. 31, 2014
Settlement of interest rate swaps							$ 132,000