Quarterly report pursuant to Section 13 or 15(d)

Marketable Securities - Additional Information (Detail)

v3.7.0.1
Marketable Securities - Additional Information (Detail) - USD ($)
6 Months Ended 12 Months Ended
Jun. 30, 2017
Dec. 31, 2016
Investments Debt And Equity Securities [Abstract]    
Realized losses $ 0 $ 0
Investments other-than-temporarily impaired $ 0 $ 0
Investments maturity period 2 years 2 years