Summary of Rental Expense (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Schedule of Rent Expense [Line Items]
Minimum rentals	$ 8,160	$ 8,914	$ 9,088
Less: Sublease rentals	(1,100)	(868)	(938)
Rental expense	$ 7,060	$ 8,046	$ 8,150