Per Share Information (Tables)

6 Months Ended

Jun. 29, 2025

Earnings Per Share [Abstract]

Schedule Of Earnings Per Share Diluted By Common Class

The following table sets forth the computation of basic and diluted income per common share: 

(In millions, except per share amounts)	Quarter ended				Year-to-date period ended
	June 29, 2025		June 30, 2024		June 29, 2025		June 30, 2024
Numerator:
Numerator for basic income per common share –
Net income attributable to ATI	$	100.7	$	81.9	$	197.7	$	148.0
Effect of dilutive securities:
3.5% Convertible Senior Notes due 2025	—		2.2		—		4.3
Numerator for diluted net income per common share –
Net income attributable to ATI after assumed conversions	$	100.7	$	84.1	$	197.7	$	152.3
Denominator:
Denominator for basic net income per common share – weighted average shares	139.8		124.4		140.7		125.3
Effect of dilutive securities:
Share-based compensation	3.3		3.1		3.0		2.8
3.5% Convertible Senior Notes due 2025	—		18.8		—		18.8
Denominator for diluted net income per common share – adjusted weighted average shares and assumed conversions	143.1		146.3		143.7		146.9
Basic net income attributable to ATI per common share	$	0.72	$	0.66	$	1.40	$	1.18
Diluted net income attributable to ATI per common share	$	0.70	$	0.58	$	1.38	$	1.04