BENEFIT PLANS: - Other (Details) $ in Millions	12 Months Ended
	Dec. 31, 2024 USD ($) plan	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)
Benefit plans
Number of noncontributory defined benefit pension plans | plan	2
Defined contribution plan and post-retirement defined benefit plans
Defined benefit plan, net periodic benefit costs
Service cost	$ 2.2	$ 2.3	$ 1.8
Interest cost	3.3	3.6	2.3
Expected return on plan assets	(5.5)	(5.9)	(3.9)
Amortization of net actuarial loss		0.1	0.1
Amortization of prior service cost/(credit)	0.2	0.7	0.2
Amortization of net loss/(gain)	0.3	0.3	0.3
Net periodic benefit cost	0.5	1.1	0.8
Change in benefit obligation:
Projected benefit obligation at beginning of year	47.4	38.6
Service cost	2.2	2.3	1.8
Interest cost	3.3	3.6	2.3
Benefits paid	(4.4)	(3.9)
Actuarial loss	1.5	1.8
Actuarial loss (gain) assumption changes	(0.3)	0.6
Inflation adjustment	(6.7)	4.4
Projected benefit obligation at end of year	43.0	47.4	38.6
Change in plan assets:
Fair value of plan assets at beginning of year	73.2	59.2
Actual return on plan assets	16.1	8.8
Employer contributions	(0.6)	(1.0)
Benefits paid	(0.7)	(0.9)
Currency exchange rate adjustment	(10.6)	7.1
Fair value of plan assets at end of year	77.4	73.2	59.2
Funded status at end of year	34.4	25.8
Amounts recognized in statement of financial position
Non-current assets	34.4	25.8
Total	34.4	25.8
Amounts recognized in accumulated other comprehensive income
Net loss (gain)	(0.3)	6.2
Prior service cost	0.8	1.1
Total, net of tax	0.5	7.3	7.8
Net loss (gain), income taxes	(0.4)	(4.7)
Reconciliation of accumulated other comprehensive income:
Accumulated other comprehensive income at beginning of plan year	7.3	7.8
Net (gain) loss ocurring during the year	(5.8)	(0.6)
Net (gain) amortized during the year	(0.3)	(0.4)
Prior service cost (credit)		0.3
Settlement	(0.1)	(0.4)
Currency exchange rate adjustment	(0.6)	0.6
Net adjustment to accumulated other comprehensive income	(6.8)	(0.5)
Accumulated other comprehensive income at end of plan year	0.5	7.3	$ 7.8
Net adjustment to accumulated other comprehensive income, income taxes	4.3	0.1
Amounts in accumulated other comprehensive income amortized and recognized as a component of net periodic benefit cost, net of income tax
Net loss / (gain)	(5.8)	(0.6)
Amortization of net (loss) gain	(0.3)	(0.4)
Amortization of prior services cost (credit)		0.3
Total amortization expenses	(6.1)	$ (0.7)
Expected Benefit Payments
2025	8.2
2026	3.4
2027	4.3
2028	4.3
2029	3.9
2030 to 2034	24.9
Total	$ 49.0
Defined contribution plan and post-retirement defined benefit plans | Expatriate Plan
Assumptions used to determine the pension obligation and other post-retirement benefits and cost
Discount rate (as a percent)	5.30%	4.65%	4.85%
Expected long-term rate of return on plan asset (as a percent)	4.00%	4.50%	4.00%
Defined contribution plan and post-retirement defined benefit plans | Mexican Health Plan
Assumptions used to determine the pension obligation and other post-retirement benefits and cost
Discount rate (as a percent)	10.19%	9.98%	10.09%
Expected long-term rate of return on plan asset (as a percent)	10.19%	9.98%	10.09%
Rate of increase in future compensation level (as a percent)	4.75%	5.00%	4.75%
Post-retirement health care plans
Defined benefit plan, net periodic benefit costs
Interest cost	$ 1.8	$ 2.2	$ 1.7
Amortization of net loss/(gain)			0.1
Net periodic benefit cost	1.8	2.2	1.8
Change in benefit obligation:
Projected benefit obligation at beginning of year	22.7	20.3
Interest cost	1.8	2.2	1.7
Benefits paid	(1.4)	(1.1)
Actuarial loss	1.8	(1.6)
Inflation adjustment	(3.7)	2.9
Projected benefit obligation at end of year	21.2	22.7	20.3
Change in plan assets:
Funded status at end of year	21.2	22.7
Amounts recognized in statement of financial position
Non-current liabilities	(21.2)	(22.7)
Total	(21.2)	(22.7)
Amounts recognized in accumulated other comprehensive income
Net loss (gain)	2.0	0.9
Total, net of tax	2.0	0.9	1.6
Net loss (gain), income taxes	(0.8)	(0.4)
Reconciliation of accumulated other comprehensive income:
Accumulated other comprehensive income at beginning of plan year	0.9	1.6
Net (gain) loss ocurring during the year	1.2	(0.8)
Currency exchange rate adjustment	(0.1)	0.2
Net adjustment to accumulated other comprehensive income	1.1	(0.7)
Accumulated other comprehensive income at end of plan year	2.0	0.9	$ 1.6
Net adjustment to accumulated other comprehensive income, income taxes	0.5	(0.4)
Amounts in accumulated other comprehensive income amortized and recognized as a component of net periodic benefit cost, net of income tax
Net loss / (gain)	1.2	(0.8)
Total amortization expenses	1.2	$ (0.8)
Expected Benefit Payments
2025	1.7
2026	1.7
2027	1.8
2028	1.8
2029	1.9
2030 to 2034	10.2
Total	$ 19.1
Post-retirement health care plans | Expatriate Plan
Assumptions used to determine the pension obligation and other post-retirement benefits and cost
Discount rate (as a percent)	5.30%	4.65%	4.85%
Post-retirement health care plans | Mexican Health Plan
Expected Benefit Payments
Assumed trend rate for covered health care benefit cost (as a percent)	5.00%
Effect of one percentage-point change in assumed other benefit cost trend rates
Effect of one percentage-point increase on total service and interest cost components	$ 2.3
Effect of one percentage-point decrease on total service and interest cost components	1.9
Effect of one percentage-point increase on post-retirement benefit obligation	21.7
Effect of one percentage-point decrease on post-retirement benefit obligation	$ 19.9
Post-retirement health care plans | Weighted average | Mexican Health Plan
Assumptions used to determine the pension obligation and other post-retirement benefits and cost
Discount rate (as a percent)	10.19%	9.98%	10.09%