Bank Borrowings - Additional Information (Detail) (Subsequent Event, USD $) In Thousands, unless otherwise specified	1 Months Ended
	Oct. 31, 2014
Line of Credit Facility [Line Items]
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%
Third Amendment
Line of Credit Facility [Line Items]
Line of credit amendment date	Oct. 31, 2014
Line of credit maturity date	Oct. 31, 2019
Line of credit, maximum borrowing capacity	$ 100,000
Second Amendment
Line of Credit Facility [Line Items]
Line of credit maturity date	Jul. 25, 2018
Line of credit, maximum borrowing capacity	$ 50,000