XML 109 R126.htm IDEA: XBRL DOCUMENT v3.20.1
Pension obligations (Schedule of fair value of plan assets) - (Details) - Pension obligations [Member] - USD ($)
$ in Thousands
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
Pension Obligations [Line Items]      
Plan assets, at fair value $ 202,119 $ 175,795 $ 341,432
Level 1 [Member]      
Pension Obligations [Line Items]      
Plan assets, at fair value 78,268 56,401  
Level 2 [Member]      
Pension Obligations [Line Items]      
Plan assets, at fair value 123,851 119,394  
Level 3 [Member]      
Pension Obligations [Line Items]      
Plan assets, at fair value 0 0  
Money market instruments [Member]      
Pension Obligations [Line Items]      
Cash and cash equivalents, amount contributed to fair value of plan assets 1,588 3,072  
Money market instruments [Member] | Level 1 [Member]      
Pension Obligations [Line Items]      
Cash and cash equivalents, amount contributed to fair value of plan assets 1,588 3,072  
Money market instruments [Member] | Level 2 [Member]      
Pension Obligations [Line Items]      
Cash and cash equivalents, amount contributed to fair value of plan assets 0 0  
Money market instruments [Member] | Level 3 [Member]      
Pension Obligations [Line Items]      
Cash and cash equivalents, amount contributed to fair value of plan assets 0 0  
Pooled equity funds [Member]      
Pension Obligations [Line Items]      
Investment funds, amount contributed to fair value of plan assets 76,680 53,329  
Pooled equity funds [Member] | Level 1 [Member]      
Pension Obligations [Line Items]      
Investment funds, amount contributed to fair value of plan assets 76,680 53,329  
Pooled equity funds [Member] | Level 2 [Member]      
Pension Obligations [Line Items]      
Investment funds, amount contributed to fair value of plan assets 0 0  
Pooled equity funds [Member] | Level 3 [Member]      
Pension Obligations [Line Items]      
Investment funds, amount contributed to fair value of plan assets 0 0  
Pooled fixed income funds [Member]      
Pension Obligations [Line Items]      
Investment funds, amount contributed to fair value of plan assets 103,646 91,854  
Pooled fixed income funds [Member] | Level 1 [Member]      
Pension Obligations [Line Items]      
Investment funds, amount contributed to fair value of plan assets 0 0  
Pooled fixed income funds [Member] | Level 2 [Member]      
Pension Obligations [Line Items]      
Investment funds, amount contributed to fair value of plan assets 103,646 91,854  
Pooled fixed income funds [Member] | Level 3 [Member]      
Pension Obligations [Line Items]      
Investment funds, amount contributed to fair value of plan assets 0 0  
Alternative investment funds [Member]      
Pension Obligations [Line Items]      
Investment funds, amount contributed to fair value of plan assets 19,438 26,871  
Alternative investment funds [Member] | Level 1 [Member]      
Pension Obligations [Line Items]      
Investment funds, amount contributed to fair value of plan assets 0 0  
Alternative investment funds [Member] | Level 2 [Member]      
Pension Obligations [Line Items]      
Investment funds, amount contributed to fair value of plan assets 19,438 26,871  
Alternative investment funds [Member] | Level 3 [Member]      
Pension Obligations [Line Items]      
Investment funds, amount contributed to fair value of plan assets 0 0  
Balanced Fund Member      
Pension Obligations [Line Items]      
Investment funds, amount contributed to fair value of plan assets 767 669  
Balanced Fund Member | Level 1 [Member]      
Pension Obligations [Line Items]      
Investment funds, amount contributed to fair value of plan assets 0 0  
Balanced Fund Member | Level 2 [Member]      
Pension Obligations [Line Items]      
Investment funds, amount contributed to fair value of plan assets 767 669  
Balanced Fund Member | Level 3 [Member]      
Pension Obligations [Line Items]      
Investment funds, amount contributed to fair value of plan assets $ 0 $ 0