Bank Borrowings - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2013
Line of Credit Facility [Line Items]
Line of credit, maximum borrowing capacity	$ 50,000
Line of credit maturity date	Jul. 25, 2018
Frequency of payments for commitment fees	Quarterly
Minimum
Line of Credit Facility [Line Items]
Commitment fees on unused line of credit, percentage	0.375%
Maximum
Line of Credit Facility [Line Items]
Commitment fees on unused line of credit, percentage	0.50%