General - Long Term Debt and Finance Lease Obligation - Senior Notes (Details) - Senior Notes - 4.400% Senior Notes due 2024 - USD ($) $ in Millions	6 Months Ended
Jun. 30, 2019	Dec. 31, 2018	Sep. 22, 2017
Debt
Debt instrument, face amount			$ 400.0
Stated interest rate (as a percent)			4.40%
Long-term debt	$ 399.3	$ 399.3
Debt instrument, maturity date	Sep. 22, 2024
Redemption price of the principal amount redeemed (as a percent)	100.00%

Face (par) amount of debt instrument at time of issuance.

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- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

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- Definition

Date when the debt instrument is scheduled to be fully repaid, in CCYY-MM-DD format.

+ References

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- Definition

Percentage price of original principal amount of debt at which debt can be redeemed by the issuer.

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- Definition

Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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