Financial Instruments - Estimated Fair Value of Financial Instruments (Details) - Fair Value, Measurements, Recurring - Derivatives Designated as Hedging Instruments - Interest rate swap - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Prepaid Expenses and Other Assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Asset Derivatives	$ 2.4	$ 3.6
Accrued Liabilities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liability Derivatives	$ 0.0	$ 0.0