Fair Value Measurements - Assets and Liabilities Measured at Fair Value on Recurring Basis (Parenthetical) (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net revenues	$ 56,524	$ 53,380	$ 52,496	$ 42,849	$ 36,561	$ 36,942	$ 37,066	$ 31,722	$ 205,249	$ 142,291	$ 95,875
Sales that has been eliminated from the accrual for contingent consideration				30,000
Load King contingent consideration [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration provision	750								750
Probability weighted average earn out payment									30
Fair value of the contingent consideration	30								30
Minimum [Member] | Load King Contingent Consideration Triggering Revenue [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net revenues									$ 30,000	$ 30,000	$ 30,000