Annual report pursuant to Section 13 and 15(d)

Income Taxes - Narrative (Detail)

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Income Taxes - Narrative (Detail) - USD ($)
 12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Income Tax      
Tax credit carryforwards $ 1,800,000    
State tax credit carryforwards subject to expire $ 900,000    
State and foreign tax credit carryforwards expiration beginning year 2017    
State and foreign tax credit carryforwards expiration ending year 2031    
State tax credit carryforwards not subject to expire $ 900,000    
Operating loss carryforwards expiration beginning year 2021    
Operating loss carryforwards expiration ending year 2037    
Excess tax benefit $ 500,000    
Penalties or interest liabilities accrued 0 $ 0  
Pretax income 1,100,000 1,600,000 $ 3,600,000
Provisional tax benefit 900,000    
Foreign earnings repatriated 10,300,000    
Provisional income tax expense on foreign earnings 1,400,000    
Tax benefits related to stock option exercises   $ 800,000 $ 3,000,000
Provisional foreign tax credit carryforwards 300,000    
Federal      
Income Tax      
Provisional income tax expense on foreign earnings 1,300,000    
State      
Income Tax      
Operating loss carryforwards expected to be utilized 13,600,000    
Net operating loss carryforwards 79,900,000    
Provisional income tax expense on foreign earnings $ 100,000