Income Taxes - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Income Taxes [Line Items]
Income Taxes Paid	$ 2,400,000	$ 990,000.0	$ 0.0
Federal statutory rate	35.00%
Net operating loss carryforwards	47,000,000
Net operating loss carryforwards, expire date	2030
Federal
Income Taxes [Line Items]
Income Taxes Paid	$ 601,000	$ 0	$ 0