Income Taxes - Activity In Unrecognized Tax Benefits (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Income Tax Contingency [Line Items]
Balance	$ 34,139
Decrease related to tax positions taken in prior years	(191)
Increase related to positions taken in the current year		34,139
Balance	$ 33,948	$ 34,139