XML 107 R61.htm IDEA: XBRL DOCUMENT v3.8.0.1
Income Taxes - Additional Information (Detail) - USD ($)
 12 Months Ended
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Income Tax [Line Items]        
Effective income tax rate   13.00% 23.00% 38.00%
US federal corporate tax rate   35.00% 35.00% 35.00%
Income tax expense recorded due to remeasurement of deferred tax balance   $ 400,000    
Unrecognized tax benefits   $ 0 $ 0  
Earliest Tax Year [Member]        
Income Tax [Line Items]        
Year of income tax returns open to examination   2007    
Latest Tax Year [Member]        
Income Tax [Line Items]        
Year of income tax returns open to examination   2017    
State Income Tax [Member]        
Income Tax [Line Items]        
Net operating loss carryforwards for state income tax   $ 1,700,000    
Scenario, Forecast [Member]        
Income Tax [Line Items]        
US federal corporate tax rate 21.00%