Income Tax Matters - Income Tax (Provision) Benefit (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025		Dec. 31, 2024		Dec. 31, 2023
Federal income tax (expense) benefit
Current federal tax (expense) benefit	$ 1.4	[1]	$ (3.5)		$ 0.0	[1]
Deferred federal income tax (expense) benefit	(30.3)		(15.9)	[1]	(16.9)	[1]
Federal benefit (expense) applied to decrease (increase) AOCI	0.8	[1]	1.9		2.5	[1]
Federal income tax (provision) benefit	(28.1)		(17.5)	[1]	(14.4)	[1]
Foreign income tax (expense) benefit
Current foreign tax (expense) benefit	(2.7)	[1]	(3.1)		(2.2)	[1]
Deferred foreign income tax (expense) benefit	(1.0)		0.6	[1]	0.1	[1]
Foreign benefit (expense) applied to decrease (increase) AOCI	1.0	[1]	0.0		0.1	[1]
Foreign income tax (provision) benefit	(2.7)		(2.5)	[1]	(2.0)	[1]
State income tax (expense) benefit
Current state tax (expense) benefit	(2.9)	[1]	(3.3)		0.6	[1]
Deferred state income tax (expense) benefit	(3.9)		0.7	[1]	0.2	[1]
State benefit (expense) applied to decrease (increase) AOCI	0.1	[1]	0.3		0.4	[1]
State income tax (provision) benefit	(6.7)		(2.3)	[1]	1.2	[1]
Total income tax (expense) benefit
Current tax (expense) benefit	(4.2)	[1]	(9.9)		(1.6)	[1]
Deferred income tax (expense) benefit	(35.2)		(14.6)	[1]	(16.6)	[1]
Benefit (expense) applied to decrease (increase) AOCI	1.9	[1]	2.2		3.0	[1]
Income tax (provision) benefit	$ (37.5)		$ (22.3)	[2],[3]	$ (15.2)	[2],[3]

[1] Adjusted to reflect the retrospective change in inventory valuation methodology from LIFO to WAC. See Note 18 for further discussion.

[2] Adjusted to reflect the retrospective change in inventory valuation methodology from LIFO to WAC. See Note 18 for further discussion.

[3] Adjusted to reflect the retrospective change in inventory valuation methodology from LIFO to WAC. See Note 18 for further discussion.