Per Share Information (Tables)

9 Months Ended

Sep. 30, 2021

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 (loss) per common share: 

(In millions, except per share amounts)	Three months ended September 30,				Nine months ended September 30,
	2021		2020		2021		2020
Numerator:
Numerator for basic income (loss) per common share –
Net income (loss) attributable to ATI	$	48.7	$	(50.1)	$	(8.4)	$	(451.6)
Effect of dilutive securities:
4.75% Convertible Senior Notes due 2022	1.1		—		—		—
3.5% Convertible Senior Notes due 2025	2.9		—		—		—
Numerator for diluted income (loss) per common share –
Net income (loss) attributable to ATI after assumed conversions	$	52.7	$	(50.1)	$	(8.4)	$	(451.6)
Denominator:
Denominator for basic net income (loss) per common share – weighted average shares	127.2		126.6		127.0		126.5
Effect of dilutive securities:
Share-based compensation	0.8		—		—		—
4.75% Convertible Senior Notes due 2022	5.8		—		—		—
3.5% Convertible Senior Notes due 2025	18.8		—		—		—
Denominator for diluted net income (loss) per common share – adjusted weighted average shares and assumed conversions	152.6		126.6		127.0		126.5
Basic net income (loss) attributable to ATI per common share	$	0.38	$	(0.40)	$	(0.07)	$	(3.57)
Diluted net income (loss) attributable to ATI per common share	$	0.35	$	(0.40)	$	(0.07)	$	(3.57)