Debt (Tables)

9 Months Ended

Sep. 30, 2021

Debt Disclosure [Abstract]

Summary of Debt

At September 30, 2021 and December 31, 2020, our long-term debt and interest rates on that debt were as follows (dollars in millions):

	September 30,		December 31,
	2021		2020
Revolving Credit Facility, due August 2021, terminated June 2021	$	—	$	—
Revolving Credit Facility, due June 2026		—		—
4.50% Senior Notes, net of discount of $0.5 million and    $0.6 million as of September 30, 2021 and December 31, 2020,    respectively, due November 2023		699.5		699.4
3.65% Senior Notes, net of discount of $0.4 million and    $0.5 million as of September 30, 2021 and December 31, 2020,    respectively, due September 2024		399.6		399.5
3.40% Senior Notes, net of discount of $1.1 million and    $1.2 million as of September 30, 2021 and December 31, 2020,    respectively, due December 2027		498.9		498.8
3.00% Senior Notes, net of discount of $0.5 million and    $0.6 million as of September 30, 2021 and December 31, 2020,    respectively, due December 2029		499.5		499.4
4.05% Senior Notes, net of discount of $3.4 million as of both    September 30, 2021 and December 31, 2020, due December 2049		396.6		396.6
3.05% Senior Notes, net of discount of $3.7 million as of    September 30, 2021, due October 2051		696.3		—
Total		3,190.4		2,493.7
Less current portion (a)		698.1		—
Less unamortized debt issuance costs		21.2		14.3
Total long-term debt	$	2,471.1	$	2,479.4

(a) The current portion of long-term debt excludes unamortized debt issuance costs of $1.4 million at September 30, 2021.