Lines of Credit and Financing Arrangements (Outstanding Debt Obligations) (Details) - USD ($)	Dec. 31, 2019	Dec. 31, 2018	Nov. 01, 2016
Current maturities of long-term debt:
Finance lease obligations	$ 7,800,000	$ 3,500,000
Domestic credit facility	321,900,000	300,800,000
Long-Term Debt:
Finance lease obligations	25,900,000	15,700,000
Total long-term debt	849,300,000	740,500,000
Debt Issuance Cost, Gross, Noncurrent	(2,100,000)	(3,200,000)
Total debt	1,171,200,000	1,041,300,000
Domestic Credit Facility [Member]
Current maturities of long-term debt:
Domestic credit facility	30,000,000.0	30,000,000.0
Debt Issuance Costs, Gross, Current	(900,000)	(700,000)
Long-Term Debt:
Total long-term debt	475,500,000	378,000,000.0
Asset Securitization [Member]
Current maturities of long-term debt:
Finance lease obligations	285,000,000.0	268,000,000.0
Senior Unsecured Notes [Member]
Debt Instrument [Line Items]
Debt instrument, face amount			$ 350,000,000.0
Long-Term Debt:
Total long-term debt	$ 350,000,000.0	$ 350,000,000.0