Fair Value Measurements - Financial Instruments (Details) - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020
Fair Value
Debt issuance costs	$ 30.2	$ 32.6
Carrying Value
Fair Value
Long-term debt	4,456.3	4,593.8
Fair Value
Fair Value
Long-term debt	$ 4,457.7	$ 4,318.2

Amount, after accumulated amortization, of debt issuance costs. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.

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