Reconciliation of Unrecognized Tax Benefits (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2012
Income Taxes [Line Items]
Balance at beginning of period	$ 1,401	$ 1,722
Decreases related to prior year tax positions	(1,401)
Increased related to current year tax positions	1,722
Balance at end of period	$ 1,722	$ 1,722