Annual report pursuant to Section 13 and 15(d)

Income Tax - Reconciliation of Unrecognized Tax Benefits of Uncertain Tax Positions (Detail)

v3.8.0.1
Income Tax - Reconciliation of Unrecognized Tax Benefits of Uncertain Tax Positions (Detail) - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Income Tax Disclosure [Abstract]      
Unrecognized tax benefits, Beginning Balance $ 715 $ 699 $ 683
Additions based on tax positions related to the current year 0 16 16
Additions based on tax positions related to prior years 0 0 0
Unrecognized tax benefits, Ending Balance $ 715 $ 715 $ 699