Annual report pursuant to Section 13 and 15(d)

Stock-Based Compensation - Summary of Stock Option Activity (Details)

v3.8.0.1
Stock-Based Compensation - Summary of Stock Option Activity (Details) - USD ($)
$ / shares in Units, $ in Thousands
12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]        
Options outstanding at beginning of period (shares) 0 0 5,000  
Granted (shares) 0 0 0  
Exercised (shares) 0 0 (5,000)  
Forfeited/expired (shares) 0 0 0  
Options outstanding end of period (shares) 0 0 0 5,000
Options exercisable at end of period (shares) 0      
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract]        
Options outstanding beginning of period (usd per share) $ 0.00 $ 0.00 $ 9.07  
Granted (usd per share) 0.00 0.00 0.00  
Exercised (usd per share) 0.00 0.00 9.07  
Forfeited/expired (usd per share) 0.00 0.00 0.00  
Options outstanding end of period (usd per share) 0.00 $ 0.00 $ 0.00 $ 9.07
Options exercisable (usd per share) $ 0.00      
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]        
Options outstanding, weighted average remaining contractual term       8 months 8 days
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Aggregate Intrinsic Value [Abstract]        
Options outstanding beginning of the period, aggregate intrinsic value $ 0 $ 0 $ 163  
Exercised, aggregate intrinsic value 0 0 124  
Options outstanding end of the period, aggregate intrinsic value 0 $ 0 $ 0 $ 163
Options exercisable end of period, aggregate intrinsic value $ 0