Annual report pursuant to Section 13 and 15(d)

Stockholders' Equity - Changes in Accumulated Other Comprehensive Income, Net of Income Taxes (Detail)

v3.8.0.1
Stockholders' Equity - Changes in Accumulated Other Comprehensive Income, Net of Income Taxes (Detail) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Accumulated Other Comprehensive Income (Loss) [Line Items]      
Beginning balance, December 31, 2016 $ 810    
Other comprehensive income (loss) before reclassifications 130    
Amounts reclassified from accumulated other comprehensive (loss) income 0    
Net current-period other comprehensive income (loss) 130 $ 353 $ 298
Ending balance, December 31, 2017 940 810  
Unrealized gains and (losses) of available-for-sale securities [Member]      
Accumulated Other Comprehensive Income (Loss) [Line Items]      
Beginning balance, December 31, 2016 (255)    
Other comprehensive income (loss) before reclassifications 193    
Amounts reclassified from accumulated other comprehensive (loss) income 0    
Net current-period other comprehensive income (loss) 193    
Ending balance, December 31, 2017 (62) (255)  
Foreign currency translation [Member]      
Accumulated Other Comprehensive Income (Loss) [Line Items]      
Beginning balance, December 31, 2016 1,065    
Other comprehensive income (loss) before reclassifications (63)    
Amounts reclassified from accumulated other comprehensive (loss) income 0    
Net current-period other comprehensive income (loss) (63)    
Ending balance, December 31, 2017 $ 1,002 $ 1,065