Debt (Tables)

3 Months Ended

Mar. 31, 2023

Debt Disclosure [Abstract]

Schedule of debt

	March 31, 2023		December 31, 2022
Debt classified as current liabilities:
Hancock County industrial revenue bonds ("IRBs") due April 1, 2028, interest payable quarterly (variable interest rates (not to exceed 12%))(1)	$	7.8	$	7.8
U.S. Revolving Credit Facility(2)	63.1		90.0
Iceland Revolving Credit Facility(3)	45.0		35.0
Iceland Term Facility(5)	12.3		13.3
Debt classified as non-current liabilities:
Grundartangi casthouse facility, net of financing fees of $0.6 million at March 31, 2023(4)	59.3		49.4
Iceland Term Facility, net of financing fees of $0.00 million and current portion at March 31, 2023(5)	—		1.2
7.5% senior secured notes due April 1, 2028, net of financing fees of $3.2 million at March 31, 2023, interest payable semiannually	246.8		246.6
2.75% convertible senior notes due May 1, 2028, net of financing fees of $1.8 million at March 31, 2023, interest payable semiannually	84.5		84.4
Total	$	518.8	$	527.7

(1) The IRBs are classified as current liabilities because they are remarketed weekly and could be required to be repaid upon demand if there is a failed remarketing. The interest rate at March 31, 2023 was 4.11%.

(2) We incur interest at a base rate plus applicable margin as defined within the agreement. The interest rate at March 31, 2023 was 8.75%.

(3) We incur interest at base rate plus applicable margin as defined within the agreement. The interest rate at March 31, 2023 was 7.66%.

(4) We incur interest at a base rate plus applicable margin as defined within the agreement. The interest rate at March 31, 2023 was 8.08%.

(5) We incur interest at a rate equal to 3.2% plus EUR EURIBOR 1 month as published by the European Money Market Institute as defined within the agreement. The interest rate at March 31, 2023 was 5.77%.

Schedule of line of credit facilities

Status of our U.S. revolving credit facility:	March 31, 2023
Credit facility maximum amount	$	250.0
Borrowing availability	169.8
Outstanding letters of credit issued	41.1
Outstanding borrowings	63.1
Borrowing availability, net of outstanding letters of credit and borrowings	65.6

Status of our Iceland revolving credit facility:	March 31, 2023
Credit facility maximum amount	$	100.0
Borrowing availability	100.0
Outstanding letters of credit issued	—
Outstanding borrowings	45.0
Borrowing availability, net of borrowings	55.0