Annual report pursuant to Section 13 and 15(d)

Stockholders' Equity - Additional Information (Detail)

v2.4.1.9
Stockholders' Equity - Additional Information (Detail) (USD $)
 12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Class of Stock [Line Items]      
Preferred Stock, shares authorized 10,000,000us-gaap_PreferredStockSharesAuthorized 10,000,000us-gaap_PreferredStockSharesAuthorized  
Preferred Stock, par value $ 0.001us-gaap_PreferredStockParOrStatedValuePerShare $ 0.001us-gaap_PreferredStockParOrStatedValuePerShare  
Voting rights Class A Common Stock entitled to one vote per share while holders of Class B Common Stock are entitled to ten votes per share on all matters submitted to a vote of stockholders.    
Class A Common Stock [Member]      
Class of Stock [Line Items]      
Common Stock, shares authorized 100,000,000us-gaap_CommonStockSharesAuthorized
/ us-gaap_StatementClassOfStockAxis
= us-gaap_CommonClassAMember 		100,000,000us-gaap_CommonStockSharesAuthorized
/ us-gaap_StatementClassOfStockAxis
= us-gaap_CommonClassAMember 		 
Common Stock, par value $ 0.001us-gaap_CommonStockParOrStatedValuePerShare
/ us-gaap_StatementClassOfStockAxis
= us-gaap_CommonClassAMember 		$ 0.001us-gaap_CommonStockParOrStatedValuePerShare
/ us-gaap_StatementClassOfStockAxis
= us-gaap_CommonClassAMember 		 
Class B Common Stock [Member]      
Class of Stock [Line Items]      
Common Stock, shares authorized 60,000,000us-gaap_CommonStockSharesAuthorized
/ us-gaap_StatementClassOfStockAxis
= us-gaap_CommonClassBMember 		60,000,000us-gaap_CommonStockSharesAuthorized
/ us-gaap_StatementClassOfStockAxis
= us-gaap_CommonClassBMember 		 
Common Stock, par value $ 0.001us-gaap_CommonStockParOrStatedValuePerShare
/ us-gaap_StatementClassOfStockAxis
= us-gaap_CommonClassBMember 		$ 0.001us-gaap_CommonStockParOrStatedValuePerShare
/ us-gaap_StatementClassOfStockAxis
= us-gaap_CommonClassBMember 		 
Certain Class B stockholders converted into Class A 399,776us-gaap_ConversionOfStockSharesConverted1
/ us-gaap_StatementClassOfStockAxis
= us-gaap_CommonClassBMember 		404,396us-gaap_ConversionOfStockSharesConverted1
/ us-gaap_StatementClassOfStockAxis
= us-gaap_CommonClassBMember 		22,880us-gaap_ConversionOfStockSharesConverted1
/ us-gaap_StatementClassOfStockAxis
= us-gaap_CommonClassBMember