Income Taxes - Summary of Changes in Deferred Tax Asset Valuation Allowance (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Income Tax Disclosure [Abstract]
Balance at Beginning of Year	$ 25,047	$ 19,153	$ 15,190
Charged to Costs and Expenses	10,965	5,894	3,963
Write-offs
Balance at End of Year	$ 36,012	$ 25,047	$ 19,153