Aggregate notional amount specified by the derivative(s). Expressed as an absolute value.

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-Publisher SEC
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Percentage points added to the reference rate to compute the variable rate on the debt instrument.

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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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Amount of unrealized gain (loss) related to the fair value of interest rate derivatives designated as fair value hedging instruments, as offset by the gain (loss) on the hedged item to the extent that the fair value hedge is determined to be effective.

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Fair value as of the balance sheet date of interest rate derivative assets, which includes all such derivative instruments in hedging and nonhedging relationships that are recognized as assets.

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The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

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Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

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The fee, expressed as a percentage of the line of credit facility, for available but unused credit capacity under the credit facility.

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Debt - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Debt Instrument [Line Items]
Fair value of interest rate swap	$ 0.4		$ 0.4		$ 2.0
Unrealized gain (loss) on interest rate cash flow hedges, pretax, accumulated other comprehensive income (loss)	(1.0)	$ 0.3	(1.6)	$ 1.3
Interest Rate Swap
Debt Instrument [Line Items]
Credit facility outstanding amount	150.0		150.0
Amended 2016 Credit Agreement \| Revolving Credit Facility
Debt Instrument [Line Items]
Credit facility maximum borrowings	400.0		400.0
Credit facility outstanding amount	208.8		208.8		209.4
Remaining borrowing capacity	179.9		179.9		179.3
Proceeds from credit facility			10.7	8.0
Gross payments under credit facility			$ 13.8	$ 34.6
Amended 2016 Credit Agreement \| Revolving Credit Facility \| Minimum
Debt Instrument [Line Items]
Line of credit facility, unused capacity, commitment fee percentage			0.15%
Amended 2016 Credit Agreement \| Revolving Credit Facility \| Maximum
Debt Instrument [Line Items]
Line of credit facility, unused capacity, commitment fee percentage			0.30%
Amended 2016 Credit Agreement \| Revolving Credit Facility \| Base Rate \| Minimum
Debt Instrument [Line Items]
Base rate borrowings margin range			0.00%
Amended 2016 Credit Agreement \| Revolving Credit Facility \| Base Rate \| Maximum
Debt Instrument [Line Items]
Base rate borrowings margin range			1.25%
Amended 2016 Credit Agreement \| Revolving Credit Facility \| LIBOR \| Minimum
Debt Instrument [Line Items]
Base rate borrowings margin range			1.00%
Amended 2016 Credit Agreement \| Revolving Credit Facility \| LIBOR \| Maximum
Debt Instrument [Line Items]
Base rate borrowings margin range			2.25%
Amended 2016 Credit Agreement \| Letter of Credit
Debt Instrument [Line Items]
Remaining borrowing capacity	11.3		$ 11.3		$ 11.3
Interest Rate Swap
Debt Instrument [Line Items]
Interest rate swap, notional amount	$ 150.0		$ 150.0