XML 171 R150.htm IDEA: XBRL DOCUMENT v3.25.2
Pension and postretirement benefits - Components of net periodic benefit cost (Details) - USD ($)
$ in Thousands
 3 Months Ended 6 Months Ended
Jun. 30, 2025
Jun. 30, 2024
Jun. 30, 2025
Jun. 30, 2024
Pension Plans        
Personnel costs:        
Service cost $ 0 $ 0 $ 0 $ 0
Other operating expenses        
Interest cost 7,411 7,558 14,821 15,117
Expected return on plan assets (8,069) (8,594) (16,138) (17,188)
Amortization of prior service cost/(credit) 0 0 0 0
Amortization of net loss (gain) 3,449 4,166 6,899 8,332
Total net periodic pension cost 2,791 3,130 5,582 6,261
OPEB Plan        
Personnel costs:        
Service cost 15 32 30 63
Other operating expenses        
Interest cost 1,291 1,421 2,582 2,843
Expected return on plan assets 0 0 0 0
Amortization of prior service cost/(credit) 0 0 0 0
Amortization of net loss (gain) (1,177) (548) (2,354) (1,096)
Total net periodic pension cost $ 129 $ 905 $ 258 $ 1,810