Income Taxes - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Income Taxes [Line Items]
U.S. federal income tax rate	34.00%
Increase in the valuation allowance	$ 4,487	$ 10,379
Net operating loss carryforwards	$ 144,759
Tax benefit recognition, description	Tax positions that meet the more likely than not threshold are measured at the largest amount of tax benefit that is greater than 50% likely of being realized upon ultimate finalization with the taxing authority.