Annual report pursuant to Section 13 and 15(d)

Share-Based Compensation (Phantom Stock) (Details)

v3.6.0.2
Share-Based Compensation (Phantom Stock) (Details) - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Unrecognized compensation cost $ 3,000    
Phantom Share Units (PSUs) [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Maximum number of shares of phantom stock available for awards 1,000,000    
Phantom shares vested 333,570 294,184  
Total liability for share awards $ 38,964 $ 25,264  
Director Phantom Stock Plan [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Share-based Liabilities Paid 278 0 $ 0
Compensation costs 2,098 (916) 2,193
Total liability for share awards 5,848 4,698  
Employee Phantom Stock Plan [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Share-based Liabilities Paid 2,442 1,682 2,401
Compensation costs 12,694 (1,612) $ 11,249
Total liability for share awards 33,116 $ 20,566  
Unrecognized compensation cost $ 11,300