Line of Credit - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Line of Credit Facility [Line Items]
Revolving line of credit, permitted	$ 25.0
Line of credit, maturity date	Jun. 30, 2013
Term facility payable (in years)	Five
Interest paid on basis points	Prime plus 50 basis points or LIBOR plus 250 basis points
Percentage of restricted dividend payments	55.00%
Line of credit	$ 0	$ 0
Prime rate basis [Member]
Line of Credit Facility [Line Items]
Interest rate spread above benchmark rate	0.50%
LIBOR basis [Member]
Line of Credit Facility [Line Items]
Interest rate spread above benchmark rate	2.50%