Line of Credit - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012
Line of Credit Facility [Line Items]
Term loan, maturity period	2 years
Before Amendment
Line of Credit Facility [Line Items]
Revolving line of credit, maximum principal amount	25.0
After Amendment
Line of Credit Facility [Line Items]
Revolving line of credit, maximum principal amount	40.0
Revolving Credit Facility | Period One
Line of Credit Facility [Line Items]
Revolving line of credit, LIBOR interest rate assessment period	30 days
Revolving Credit Facility | Period Two
Line of Credit Facility [Line Items]
Revolving line of credit, LIBOR interest rate assessment period	60 days
Revolving Credit Facility | Period Three
Line of Credit Facility [Line Items]
Revolving line of credit, LIBOR interest rate assessment period	90 days
Revolving Credit Facility | Libor Plus Applicable Margin
Line of Credit Facility [Line Items]
Revolving line of credit, interest plus LIBOR	1.21%