Schedule II - Valuation and Qualifying Accounts (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at beginning of year	$ 1,952		$ 2,134		$ 2,132
Charged to costs and expenses	4		202		274
Deductions/net charge-offs	(119)	[1]	(384)	[1]	(272)	[1]
Balance at the end of year	$ 1,837		$ 1,952		$ 2,134

[1] Represents write-off of bad debts net of recoveries