Allowance for Doubtful Accounts (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Allowance for Doubtful Accounts [Line Items]
Balance at Beginning of Year	$ 800	$ 504	$ 546
Additions	202	390	153
Deductions	570	94	195
Balance at End of Year	$ 432	$ 800	$ 504