Quarterly report pursuant to Section 13 or 15(d)

Soft Dollar Arrangements - Additional Information (Detail)

v3.7.0.1
Soft Dollar Arrangements - Additional Information (Detail) - USD ($)
$ in Thousands
 3 Months Ended 6 Months Ended
Jun. 30, 2017
Jun. 30, 2016
Jun. 30, 2017
Jun. 30, 2016
Soft Dollar Arrangements [Abstract]        
Soft dollar credits $ 178 $ 199 $ 356 $ 398