Debt Security Held To Maturity - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2013	Dec. 31, 2012
Schedule of Held-to-maturity Securities [Line Items]
Debt security, held to maturity, at cost	$ 15,000	$ 15,000
Maturity date	Oct. 31, 2016
Debt security bears interest at the rate	The debt security pays interest quarterly at the rate of 4.0% above the three-month London Interbank Offered Rate ("LIBOR").
Debt security, held to maturity, fair value	$ 14,216
Debt security, held to maturity, stated interest rate	4.00%