Shareholders' equity (reclassification adjustments) (Details) - USD ($) $ in Millions |
3 Months Ended | 6 Months Ended | ||
|---|---|---|---|---|
Jun. 30, 2026 |
Jun. 30, 2025 |
Jun. 30, 2026 |
Jun. 30, 2025 |
|
| Amounts reclassified from accumulated other comprehensive loss | ||||
| Prior service credit | $ 0.4 | $ 0.4 | $ 0.7 | $ 0.7 |
| Net actuarial loss | 0.0 | (0.2) | (0.1) | (0.4) |
| Total amortization | 0.4 | 0.2 | 0.6 | 0.3 |
| Tax expense | (0.2) | (0.1) | (0.2) | (0.2) |
| Amortization of postretirement benefit plan items, net of tax | 0.2 | 0.1 | 0.4 | 0.1 |
| Total reclassifications, net of tax | $ 0.2 | $ 0.1 | $ 0.4 | $ 0.1 |
| X | ||||||||||
- Definition Reclassification adjustments from accumulated other comprehensive income No definition available.
|
| X | ||||||||||
- Definition Amount, before tax, of reclassification adjustment from accumulated other comprehensive (income) loss for prior service cost (credit) of defined benefit plan. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
|
| X | ||||||||||
- Definition Amount, before tax, of reclassification adjustment from accumulated other comprehensive (income) loss for net period benefit cost (credit) of defined benefit plan. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
|
| X | ||||||||||
- Definition Amount, before tax, of reclassification adjustment from accumulated other comprehensive income (loss) for gain (loss) of defined benefit plan. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
|
| X | ||||||||||
- Definition Amount, after tax, of reclassification adjustment from accumulated other comprehensive (income) loss for net periodic benefit cost (credit) of defined benefit plan. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
|
| X | ||||||||||
- Definition Amount of tax (expense) benefit for reclassification adjustment from accumulated other comprehensive (income) loss of defined benefit plan. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
|
| X | ||||||||||
- Definition Amount after tax of reclassification adjustments of other comprehensive income (loss) attributable to parent. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
|