Fair value, after offset of derivative asset, of financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset, elected not to be and before offset against a right to receive collateral under a master netting arrangement. Includes liabilities elected not to be offset. Excludes liabilities not subject to a master netting arrangement.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Nominal or face amount used to calculate payment on derivative.

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- Definition

Period remaining until the derivative contract matures, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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The portion of the carrying amount of long-term borrowings outstanding as of the balance sheet date, including current maturities, which accrues interest at a rate subject to change from time to time.

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Number of interest rate derivative instruments held by the entity at the reporting date.

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Derivative Instruments - Interest rate swap agreement (Details) $ in Millions	12 Months Ended
	Dec. 31, 2019 USD ($) item	Oct. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2016 USD ($)
Interest rate contracts
Derivative instruments
Borrowings at variable interest rates	$ 404.3		$ 427.0
Number of interest rate swap agreements \| item	2
Notional amount outstanding		$ 100.0		$ 100.0
Net fair value of swap liability	$ 1.7		$ 1.7
2016 Swap Agreement
Derivative instruments
Remaining maturity term	16 months
2019 Swap Agreement
Derivative instruments
Remaining maturity term	54 months