Quarterly report pursuant to Section 13 or 15(d)

Income Taxes - Additional Information (Detail)

v3.8.0.1
Income Taxes - Additional Information (Detail) - USD ($)
3 Months Ended 12 Months Ended
Mar. 31, 2018
Mar. 31, 2017
Dec. 31, 2017
Income Tax Disclosure [Abstract]      
Liability for unrecognized tax benefit, including related estimates of penalties and interest $ 0 $ 0  
Income tax provision (benefit) $ 32,000 $ 40,000  
Projected annual effective tax rate 0.60% 1.00%  
Statutory tax rate 21.00% 34.00% 34.00%