Debt and Other Financing Arrangements - Financial Ratios under Senior Credit Facility (Details)	3 Months Ended
	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018
Required
Financial Ratios Under Senior Credit Facility [Line Items]
Leverage Ratio (maximum)	3.5	3.5	3.5
Interest Coverage Ratio (minimum)	2.75	2.75	2.75
Actual
Financial Ratios Under Senior Credit Facility [Line Items]
Leverage Ratio (maximum)	2.05	1.79	2.09
Interest Coverage Ratio (minimum)	10.05	10.84	9.87