Debt and Credit Facility (Tables)

9 Months Ended

Sep. 30, 2023

Debt Disclosure [Abstract]

Summary of Senior Notes

The following table summarizes key details of our Senior Notes:

				Outstanding (in millions of dollars)
	Issuance Date	Maturity	Effective Interest Rate	As of September 30, 2023			As of December 31, 2022
4.50% Senior Notes	May 2021	June 2031	4.7%	$	550.0		$	550.0
4.625% Senior Notes	November 2019	March 2028	4.8%		500.0			500.0
Total debt					1,050.0			1,050.0
Unamortized issuance costs					(10.6	)		(11.9	)
Total carrying amount				$	1,039.4		$	1,038.1

Summary of Fair Value of Outstanding Senior Notes

The following table presents the fair value of our outstanding Senior Notes, which are Level 1 liabilities (in millions of dollars):

	As of September 30, 2023		As of December 31, 2022
4.50% Senior Notes	$	435.7	$	438.7
4.625% Senior Notes	$	436.6	$	440.4

Schedule of Availability and Usage of Revolving Credit Facility

The following table summarizes availability and usage of our Revolving Credit Facility as determined by a borrowing base calculated as of September 30, 2023 (in millions of dollars):

Revolving Credit Facility borrowing commitment	$	575.0
Borrowing base availability	$	556.1
Less: Outstanding borrowings under Revolving Credit Facility		—
Less: Outstanding letters of credit under Revolving Credit Facility		(26.6	)
Remaining borrowing availability	$	529.5

Summary of Interest Expense Relating to Senior Notes and Revolving Credit Facility

The following table presents interest expense relating to our Senior Notes and Revolving Credit Facility (in millions of dollars):

	Quarter Ended September 30,						Nine Months Ended September 30,
	2023			2022			2023			2022
Senior Notes, including debt issuance cost amortization	$	12.4		$	12.4		$	37.2		$	37.2
Revolving Credit Facility, including commitment fees and finance cost amortization		0.8			0.6			2.9			1.6
Interest expense capitalized as construction in progress		(1.8	)		(0.9	)		(4.7	)		(2.3	)
Total interest expense	$	11.4		$	12.1		$	35.4		$	36.5