Annual report pursuant to Section 13 and 15(d)

Share-Based Compensation (Narrative) (Details)

v3.10.0.1
Share-Based Compensation (Narrative) (Details) - USD ($)
$ / shares in Units, $ in Thousands
12 Months Ended
May 10, 2018
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
May 12, 2011
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Payments to settle vested liability share-based awards   $ 4,990 $ 13,173 $ 10,300  
Cash-settleable restricted stock unit awards   $ 1,390 $ 4,621    
Market-based RSUs | Vesting Minimum          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Share-based compensation arrangement vesting rights, percentage   0.00%      
Market-based RSUs | Vesting Maximum          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Share-based compensation arrangement vesting rights, percentage   200.00%      
Cash-settleable RSU awards          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Weighted average period over which expense is expected to be recognized   2 years      
Cash-settleable RSU awards | Vesting Minimum          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Share-based compensation arrangement vesting rights, percentage   0.00%      
Cash-settleable RSU awards | Vesting Maximum          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Share-based compensation arrangement vesting rights, percentage   200.00%      
Unvested RSUs          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Weighted average period over which expense is expected to be recognized   2 years      
Stock options          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Number of years company issued no stock options   3 years      
Outstanding, shares (in shares)       15,000  
Outstanding, end of year, weighted average exercise price per option       $ 14.37  
Outstanding options weighted-average remaining contract life per unit       3 months 18 days  
RSU equity awards          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Weighted average period over which expense is expected to be recognized   1 year 10 months 6 days      
Granted (in shares)   872,000 1,173,094 684,090  
Granted, grant date fair value per share (usd per share)   $ 13.89 $ 12.25 $ 12.63  
Fair value of shares vested   $ 6,344 $ 9,045 $ 2,608  
Vested in period (in shares)   506,000      
RSU equity awards | Vesting Minimum          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Share-based compensation arrangement vesting rights, percentage   0.00%      
RSU equity awards | Vesting Maximum          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Share-based compensation arrangement vesting rights, percentage   200.00%      
Market-based Cash-settleable RSUs Awards          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Vested in period (in shares)   207,261 335,471    
Market-based Cash-settleable RSUs Awards | Minimum          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Share-based compensation arrangement vesting rights, percentage   100.00% 142.00%    
Market-based Cash-settleable RSUs Awards | Maximum          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Share-based compensation arrangement vesting rights, percentage   163.00% 200.00%    
Market-based Cash-settleable RSUs Awards | Vested at between 100% to 163%          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Payments to settle vested liability share-based awards   $ 89      
Cash-settleable restricted stock unit awards   1,296      
Market-based Cash-settleable RSUs Awards | Vested at between 142% to 200%          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Payments to settle vested liability share-based awards   $ 3,062 $ 3,986    
Non-Market Based Cash-settleable RSU Awards          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Vested in period (in shares)   129,753 43,031    
Payments to settle vested liability share-based awards   $ 1,834 $ 526    
2011 Plan          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Number of shares available for grant (in shares)   9,806,953      
Number of shares authorized (in shares)         5,141,000
2018 Plan          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Number of shares authorized (in shares) 9,400,000 10,722,742      
Increase (decrease) in shares 1,322,742