Quarterly report pursuant to Section 13 or 15(d)

Cost-Method Investment (Additional Information) (Detail)

v3.10.0.1
Cost-Method Investment (Additional Information) (Detail) - USD ($)
Sep. 30, 2018
Jun. 30, 2018
Dec. 31, 2017
Cost Method Investment Ownership Percentage   1.00%  
Cost Method Investment Additional Ownership Percentage   4.00%  
Cost Method Investments, Original Cost $ 250,000 $ 250,000 $ 0