XML 86 R72.htm IDEA: XBRL DOCUMENT v3.8.0.1
Income Taxes - Reconciliation of Beginning and Ending Amounts of Unrecognized Tax Benefits (Detail) - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Income Tax Disclosure [Abstract]    
Beginning balance $ 1,007  
Increases related to current year tax positions 1,971 $ 605
Increases related to prior year tax positions 123 402
Ending balance $ 3,101 $ 1,007