Debt and Financing Obligation - Revolving Facility Narrative (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
Outstanding balance	$ 739.9	$ 800.5
$400.0 million revolving credit facility, due 2024 ("Revolving Facility") \| Line of Credit \| Revolving Credit Facility
Debt Instrument [Line Items]
Letters of credit outstanding under revolving facility	11.8
Outstanding balance	104.3	$ 143.3
Remaining borrowing capacity	283.9
$400.0 million revolving credit facility, due 2024 ("Revolving Facility") \| Line of Credit \| Letter of Credit
Debt Instrument [Line Items]
Outstanding balance	$ 11.5

Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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-Section 50
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
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The total amount of the contingent obligation under letters of credit outstanding as of the reporting date.

+ References

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Amount of borrowing capacity currently available under the credit facility (current borrowing capacity less the amount of borrowings outstanding).

+ References

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-Name Accounting Standards Codification
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-SubTopic 10
-Section S99
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