v3.26.1
Components of Net Periodic Benefit Cost (Details) - USD ($)
$ in Thousands
 3 Months Ended 6 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2026
Jun. 30, 2025
QRP        
Defined Benefit Plan Disclosure [Line Items]        
Service cost $ 6,467 $ 6,099 $ 12,934 $ 12,197
Interest cost 16,726 16,397 33,452 32,794
Expected return on plan assets (22,221) (22,581) (44,442) (45,163)
Amortization of prior service costs 0 0 0 0
Amortization of net actuarial loss (gain) 2,295 752 4,590 1,504
Net periodic benefit cost 3,267 667 6,534 1,332
SERP        
Defined Benefit Plan Disclosure [Line Items]        
Service cost 52 58 104 116
Interest cost 589 596 1,178 1,192
Expected return on plan assets 0 0 0 0
Amortization of prior service costs 0 0 0 0
Amortization of net actuarial loss (gain) 334 270 668 540
Net periodic benefit cost 975 924 1,950 1,848
PBOP        
Defined Benefit Plan Disclosure [Line Items]        
Service cost 299 292 598 584
Interest cost 835 857 1,670 1,713
Expected return on plan assets (694) (624) (1,388) (1,248)
Amortization of prior service costs 44 44 88 88
Amortization of net actuarial loss (gain) (103) (79) (206) (157)
Net periodic benefit cost $ 381 $ 490 $ 762 $ 980