Long-Term Debt and Short-Term Debt - Summary of Long-Term Debt and Short-Term Debt (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Debt Instrument [Line Items]
Total debt	$ 49,752	$ 36,477
Less current maturities of long-term debt	13,752	10,477
Long-term debt, excluding current maturities of long-term debt	36,000	26,000
October 26, 2017 [Member]
Debt Instrument [Line Items]
Borrowings under our $100,000 revolving credit facility bearing interest at a floating rate equal to LIBOR (0.1875% at March 31, 2014) plus an applicable margin of 1.25% at March 31, 2014, expiring October 26, 2017.	24,038	10,763
April 26, 2014 [Member]
Debt Instrument [Line Items]
Borrowings under our $40,000 aggregate principal amount of fixed rate notes bearing interest at a fixed rate of 4.89% maturing on April 26, 2014. Annual principal payments of $5,714 began on April 26, 2008 and extend through the date of maturity.	5,714	5,714
December 20, 2018 [Member]
Debt Instrument [Line Items]
Borrowings under our $20,000 aggregate principal amount of fixed rate notes bearing interest at a fixed rate of 4.64% maturing on December 20, 2018. Annual principal payments of $4,000 will begin on December 22, 2014 and extend through the date of maturity.	$ 20,000	$ 20,000