Annual report pursuant to Section 13 and 15(d)

Income Taxes - Additional Information (Detail)

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Income Taxes - Additional Information (Detail) (USD $)
 12 Months Ended
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2011
Dec. 31, 2010
Income Tax [Line Items]        
Stock-based compensation $ 12,986,000 $ 9,984,000 $ 7,368,000  
Federal tax credit carryforward expiration date 2024      
Federal alternative minimum tax credit carryforward 200,000      
Deferred tax assets, valuation allowance, noncurrent 6,700,000      
Unrecognized tax benefits 5,462,000 3,750,000 3,020,000 1,184,000
Unrecognized tax benefits that would impact effective tax rate 4,600,000      
Taxable income adjustment from tax examination 0      
Federal Tax
        
Income Tax [Line Items]        
Operating Loss Carryforwards 27,700,000      
Stock-based compensation 7,800,000      
Operating loss carryforwards, expiration dates Dec. 31, 2026      
Tax credit carryforward, amount 8,300,000      
State Tax
        
Income Tax [Line Items]        
Operating Loss Carryforwards 24,000,000      
Stock-based compensation 3,800,000      
Operating loss carryforwards, expiration dates Dec. 31, 2019      
Tax credit carryforward, amount $ 8,700,000