Per Share Information (Tables)

3 Months Ended

Mar. 31, 2018

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:

	Three months ended
(In millions, except per share amounts)	March 31,
	2018		2017
Numerator:
Numerator for basic income per common share –
Net income attributable to ATI	$	58.0	$	17.5
Effect of dilutive securities:
4.75% Convertible Senior Notes due 2022	3.2		3.0
Numerator for diluted income per common share –
Net income attributable to ATI after assumed conversions	$	61.2	$	20.5
Denominator:
Denominator for basic net income per common share – weighted average shares	125.0		107.5
Effect of dilutive securities:
Share-based compensation	0.6		0.8
4.75% Convertible Senior Notes due 2022	19.9		19.9
Denominator for diluted net income per common share – adjusted weighted average shares and assumed conversions	145.5		128.2
Basic net income attributable to ATI per common share	$	0.46	$	0.16
Diluted net income attributable to ATI per common share	$	0.42	$	0.16