Long-Term Debt, Finance Lease and Deferred Financing Obligations - Credit Agreement - Contractual Maturities (Details) - Unsecured Debt - 2017 Credit Agreement, senior unsecured term loan facility $ in Millions	Dec. 31, 2020 USD ($)
Long-term Debt, Fiscal Year Maturity
2021	$ 0.0
2022	5.0
2023	$ 258.1