Debt (Tables)

12 Months Ended

Dec. 31, 2021

Debt Disclosure [Abstract]

Schedule of debt

Debt at December 31, 2021 and 2020 was as follows:

(In millions)	2021		2020
Allegheny Technologies 5.875% Senior Notes due 2023 (a)	$	—	$	500.0
Allegheny Technologies 5.875% Senior Notes due 2027	350.0		350.0
Allegheny Technologies 5.125% Senior Notes due 2031	350.0		—
Allegheny Technologies 4.875% Notes due 2029	325.0		—
Allegheny Technologies 3.5% Convertible Senior Notes due 2025	291.4		291.4
Allegheny Technologies 4.75% Convertible Senior Notes due 2022	84.2		84.2
Allegheny Ludlum 6.95% Debentures due 2025 (b)	150.0		150.0
Term Loan due 2024	200.0		200.0
U.S. revolving credit facility	—		—
Foreign credit agreements	27.4		5.5
Finance leases and other	85.7		48.0
Debt issuance costs	(20.8)		(14.5)
Equity component of convertible debt	—		(46.8)
Total short-term and long-term debt	1,842.9		1,567.8
Short-term debt and current portion of long-term debt	131.3		17.8
Total long-term debt	$	1,711.6	$	1,550.0

(a)Bearing interest at 7.875% effective February 15, 2016.

(b)The payment obligations of these debentures issued by Allegheny Ludlum, LLC are fully and unconditionally guaranteed by ATI.

Interest Income and Interest Expense Disclosure

Interest expense on the 2025 Convertible Notes was as follows:

	Fiscal year ended December 31,
(in millions)	2021		2020
Contractual coupon rate	$	10.2	$	5.3
Amortization of debt issuance costs	1.7		0.7
Total interest expense	$	11.9	$	6.0

Interest expense on the 2022 Convertible Notes was as follows:

	Fiscal year ended December 31,
(in millions)	2021		2020		2019
Contractual coupon rate	$	4.0	$	8.6	$	13.7
Amortization of debt issuance costs	0.5		1.0		1.5
Total interest expense	$	4.5	$	9.6	$	15.2