CONDENSED CONSOLIDATED STATEMENT OF CHANGES IN EQUITY - USD ($) $ in Millions		Total	Capital stock	Treasury stock	Additional paid-in capital	Accumulated deficit	Accumulated other comprehensive income (loss)	[1]
Beginning balance at Dec. 31, 2023		$ 1,771.0	$ 1,672.5	$ (80.1)	$ 1,030.6	$ (851.8)	$ (0.2)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of capital stock		3.9	5.4		(1.5)
Repurchase of capital stock for cancellation	[2]	(13.8)	(6.4)		(7.4)
Purchase of treasury stock for stock-based compensation (SBC) plans	[3]	(94.1)		(94.1)
SBC cash settlement		(69.0)			(69.0)
SBC		23.3		79.2	(55.9)
Net earnings for the period		91.8				91.8
Other comprehensive income (loss)		(3.8)					(3.8)
Ending balance at Mar. 31, 2024		1,709.3	1,671.5	(95.0)	896.8	(760.0)	(4.0)
Beginning balance at Dec. 31, 2024		1,896.0	1,632.8	(92.9)	797.5	(423.8)	(17.6)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of capital stock		0.0	5.1		(5.1)
Repurchase of capital stock for cancellation	[4]	(76.2)	(9.2)		(67.0)
Purchase of treasury stock for stock-based compensation (SBC) plans		(221.6)		(221.6)
SBC cash settlement		(156.0)			(156.0)
SBC		26.5		108.9	(82.4)
Net earnings for the period		86.2				86.2
Other comprehensive income (loss)		1.9					1.9
Ending balance at Mar. 31, 2025		$ 1,556.8	$ 1,628.7	$ (205.6)	$ 487.0	$ (337.6)	$ (15.7)

[1] Accumulated other comprehensive income (loss) is net of tax (see note 10).

[2] Consists of $16.5 paid to repurchase common shares for cancellation during the first quarter of 2024, offset in part by the reversal of $2.7 accrued at December 31, 2023 for the estimated contractual maximum quantity of permitted common share repurchases (Contractual Maximum Quantity) under an automatic share purchase plan (ASPP) executed in December 2023 for such purpose (see note 9).

[3] Consists of $101.6 paid to repurchase common shares for delivery obligations under our SBC plans during the first quarter of 2024, offset in part by the reversal of $7.5 accrued at December 31, 2023 for the estimated Contractual Maximum Quantity under an ASPP executed in September 2023 for such purpose (see note 9).

[4] Consists of $75.0 paid to repurchase common shares for cancellation during the first quarter of 2025 and $1.2 accrued at March 31, 2025 for share buyback taxes (see note 9).