Quarterly report pursuant to Section 13 or 15(d)

Equity Method Investments - Additional Information (Detail)

v3.8.0.1
Equity Method Investments - Additional Information (Detail) - USD ($)
$ in Thousands
3 Months Ended 9 Months Ended
Sep. 30, 2017
Sep. 30, 2016
Sep. 30, 2017
Sep. 30, 2016
Equity [Abstract]        
Income (loss) from equity method investments $ 6,876 $ 1,331 $ 19,424 $ 2,677