Annual report pursuant to Section 13 and 15(d)

Share-Based Compensation (Summary of Liability for Cash-Settled RSU Awards) (Details)

v3.8.0.1
Share-Based Compensation (Summary of Liability for Cash-Settled RSU Awards) (Details) - Cash-settleable RSU awards - USD ($)
$ in Thousands
Dec. 31, 2017
Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Total cash-settled RSU awards $ 8,111 $ 16,990
Current Liabilities    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Cash-settled RSU awards (current) 4,621 8,919
Non-current Liabilities    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Cash-settled RSU awards (non-current) $ 3,490 $ 8,071