Per Share Information (Tables)

6 Months Ended

Jun. 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 loss per common share: 

(In millions, except per share amounts)	Three months ended June 30,				Six months ended June 30,
	2021		2020		2021		2020
Numerator:
Numerator for basic loss per common share –
Net loss attributable to ATI	$	(49.2)	$	(422.6)	$	(57.1)	$	(401.5)
Effect of dilutive securities:
4.75% Convertible Senior Notes due 2022	—		—		—		—
3.5% Convertible Senior Notes due 2025	—		—		—		—
Numerator for diluted loss per common share –
Net loss attributable to ATI after assumed conversions	$	(49.2)	$	(422.6)	$	(57.1)	$	(401.5)
Denominator:
Denominator for basic net loss per common share – weighted average shares	127.1		126.6		127.0		126.4
Effect of dilutive securities:
Share-based compensation	—		—		—		—
4.75% Convertible Senior Notes due 2022	—		—		—		—
3.5% Convertible Senior Notes due 2025	—		—		—		—
Denominator for diluted net loss per common share – adjusted weighted average shares and assumed conversions	127.1		126.6		127.0		126.4
Basic net loss attributable to ATI per common share	$	(0.39)	$	(3.34)	$	(0.45)	$	(3.18)
Diluted net loss attributable to ATI per common share	$	(0.39)	$	(3.34)	$	(0.45)	$	(3.18)