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 Period	$ 6,927	$ 12,113	$ 7,593
Charged to Costs and Expenses	821	4,024	10,138
Deductions	1,391	9,210	5,618
Balance at End of Period	$ 6,357	$ 6,927	$ 12,113