Bank Borrowings - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Debt Disclosure [Line Items]
Current credit facility, agreement date	2010-01-29
Line of credit, maximum borrowing capacity	$ 10,000
Commitment fees on unused line of credit, percentage	0.50%		0.375%
Frequency of payments for commitment fees	Quarterly
Commitment fees	$ 51	$ 47	$ 38