Annual report pursuant to Section 13 and 15(d)

Stockholders' Equity - Additional Information (Detail)

v3.8.0.1
Stockholders' Equity - Additional Information (Detail) - USD ($)
$ in Thousands
 3 Months Ended 12 Months Ended
Mar. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Class of Stock [Line Items]        
Common stock, outstanding   21,352,000 20,893,000  
Common stock issued during the period, value     $ 16,192 $ 9,507
Preferred stock authorized to issue   5,000,000    
Preferred stock, shares outstanding   0 0 0
RVL One Limited Liability Company        
Class of Stock [Line Items]        
Common stock, outstanding   8,670,386    
Common stock share outstanding owned   41.00%    
RVL One Limited Liability Company | Scenario, forecast        
Class of Stock [Line Items]        
Common stock, outstanding 9,670,386      
Common stock share outstanding owned 43.00%      
Common stock issued during the period 1,000,000      
Common stock issued during the period, value $ 3,600