Annual report pursuant to Section 13 and 15(d)

Summary of Significant Accounting Policies - Reconciliation between U.S. Statutory Federal Income Tax Rate and Effective Income Tax Rate (Detail)

v2.4.1.9
Summary of Significant Accounting Policies - Reconciliation between U.S. Statutory Federal Income Tax Rate and Effective Income Tax Rate (Detail)
12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Accounting Policies [Abstract]      
U.S. statutory federal income tax rate 0.00%us-gaap_EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate 0.00%us-gaap_EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate 34.00%us-gaap_EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate
State taxes, net of U.S. federal income tax benefit 26.90%us-gaap_EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes 41.70%us-gaap_EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes 4.00%us-gaap_EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes
Other adjustments 0.00%us-gaap_EffectiveIncomeTaxRateReconciliationOtherAdjustments 473.40%us-gaap_EffectiveIncomeTaxRateReconciliationOtherAdjustments (4.70%)us-gaap_EffectiveIncomeTaxRateReconciliationOtherAdjustments
Effective tax rate 26.90%us-gaap_EffectiveIncomeTaxRateContinuingOperations 515.10%us-gaap_EffectiveIncomeTaxRateContinuingOperations 33.30%us-gaap_EffectiveIncomeTaxRateContinuingOperations