Annual report pursuant to Section 13 and 15(d)

Equity Incentive Plan (Details)

v3.10.0.1
Equity Incentive Plan (Details)
12 Months Ended
Nov. 01, 2017
Dec. 31, 2018
$ / shares
shares
Dec. 31, 2017
$ / shares
shares
Dec. 31, 2016
$ / shares
shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Number of restricted common shares reserved for issuance under equity incentive plan (in shares)   6,500,000    
Reverse stock split, conversion ratio 0.50      
Number of restricted common shares granted during period under equity incentive plan (in shares)   996,924 671,845  
Weighted average grant date fair value of restricted common shares granted during period under equity incentive plan (in usd per share) | $ / shares   $ 14.96 $ 17.60  
Director [Member]        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Number of restricted common shares granted during period under equity incentive plan (in shares)   55,553 34,559 40,869
Weighted average grant date fair value of restricted common shares granted during period under equity incentive plan (in usd per share) | $ / shares   $ 15.48 $ 19.82 $ 16.86
Key Employees [Member]        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Number of restricted common shares granted during period under equity incentive plan (in shares)   941,371 637,286 968,761
Weighted average grant date fair value of restricted common shares granted during period under equity incentive plan (in usd per share) | $ / shares   $ 15.12 $ 17.48 $ 15.04
Award vesting period of restricted common shares granted during period under equity incentive plan   3 years