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Earnings Per Share Attributable to Common Stockholders - Additional Information (Detail)
 12 Months Ended 0 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Apr. 04, 2014
Stock Option        
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]        
Antidilutive securities excluded from computation of earnings per share, amount 407,328us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount
/ us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis
= us-gaap_StockOptionMember		 477,452us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount
/ us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis
= us-gaap_StockOptionMember		 1,330,521us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount
/ us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis
= us-gaap_StockOptionMember		  
Restricted Stock Units        
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]        
Antidilutive securities excluded from computation of earnings per share, amount 657us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount
/ us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis
= us-gaap_RestrictedStockUnitsRSUMember		      
Common stock | IPO        
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]        
Number of Series A preferred stock shares converted into common stock       19,284,113us-gaap_ConversionOfStockSharesIssued1
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_CommonStockMember
/ us-gaap_SubsidiarySaleOfStockAxis
= us-gaap_IPOMember