XML 83 R71.htm IDEA: XBRL DOCUMENT v3.21.2
Fair value measurements (Details 4) - USD ($)
$ in Thousands
Jun. 30, 2021
Dec. 31, 2020
Jun. 30, 2020
Fair value, balance sheet grouping [Line Items]      
Long-term debt $ 2,337,049 $ 2,213,130 $ 2,281,876
Carrying amount      
Fair value, balance sheet grouping [Line Items]      
Long-term debt 2,337,049 2,213,130 2,281,876
Fair value      
Fair value, balance sheet grouping [Line Items]      
Long-term debt, fair value $ 2,616,232 $ 2,537,289 $ 2,563,734