Per Share Information (Tables)

3 Months Ended

Mar. 31, 2022

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 March 31,
	2022		2021
Numerator:
Numerator for basic income (loss) per common share –
Net income (loss) attributable to ATI	$	30.9	$	(7.9)
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	$	34.9	$	(7.9)
Denominator:
Denominator for basic net income (loss) per common share – weighted average shares	126.4		126.8
Effect of dilutive securities:
Share-based compensation	1.8		—
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	152.8		126.8
Basic net income (loss) attributable to ATI per common share	$	0.24	$	(0.06)
Diluted net income (loss) attributable to ATI per common share	$	0.23	$	(0.06)