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Stock-based Compensation - Additional Information (Detail)
$ / shares in Units, $ in Thousands
1 Months Ended 3 Months Ended 6 Months Ended
Jun. 01, 2014
shares
Feb. 28, 2017
installment
$ / shares
shares
Jun. 30, 2017
USD ($)
shares
Jun. 30, 2016
USD ($)
Jun. 30, 2017
USD ($)
shares
Jun. 30, 2016
USD ($)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Compensation expense associated with grants | $     $ 600 $ 400 $ 1,136 $ 868
Restricted Stock Awards [Member]            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Compensation expense associated with grants | $     600 $ 400 1,100 $ 900
Unamortized stock-based compensation expense related to unvested awards | $     $ 4,800   $ 4,800  
Weighted-average remaining vesting period         2 years 2 months  
Ensign Employees [Member]            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Restricted stock award conversion ratio related to the spin-off 1          
Ensign Employees [Member] | Restricted Stock Awards [Member]            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Stock awards unvested during spin-off (in shares) 207,580          
Shares vested (in shares)         15,860  
Unvested stock awards outstanding (in shares)     26,320   26,320  
Member of Board of Directors [Member] | Restricted Stock Awards [Member]            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Number of restricted stock awards granted (in shares)   233,768        
Restricted stock award grant date fair value (in usd per share) | $ / shares   $ 15.21        
Number of equal annual vesting installments | installment   3