v3.10.0.1
Financial Instruments - Assets and Liabilities Measured at Fair Value (Details) - USD ($)
$ in Millions
Jun. 30, 2018
Dec. 31, 2017
Liabilities:    
Contingent consideration - other long-term liabilities $ 70.7 $ 71.3
Fair Value, Measurements, Recurring    
Assets:    
Total assets 123.1 152.5
Liabilities:    
Contingent consideration - other long-term liabilities 72.7 73.3
Total liabilities 74.2 73.5
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets (Level 1)    
Assets:    
Total assets 42.8 30.3
Liabilities:    
Contingent consideration - other long-term liabilities 0.0 0.0
Total liabilities 0.0 0.0
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2)    
Assets:    
Total assets 80.3 122.2
Liabilities:    
Contingent consideration - other long-term liabilities 0.0 0.0
Total liabilities 1.5 0.2
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3)    
Assets:    
Total assets 0.0 0.0
Liabilities:    
Contingent consideration - other long-term liabilities 72.7 73.3
Total liabilities 72.7 73.3
Fair Value, Measurements, Recurring | Fuel Hedges    
Assets:    
Hedge derivatives - other current assets 2.6 3.0
Fair Value, Measurements, Recurring | Fuel Hedges | Quoted Prices in Active Markets (Level 1)    
Assets:    
Hedge derivatives - other current assets 0.0 0.0
Fair Value, Measurements, Recurring | Fuel Hedges | Significant Other Observable Inputs (Level 2)    
Assets:    
Hedge derivatives - other current assets 2.6 3.0
Fair Value, Measurements, Recurring | Fuel Hedges | Significant Unobservable Inputs (Level 3)    
Assets:    
Hedge derivatives - other current assets 0.0 0.0
Fair Value, Measurements, Recurring | Commodity Contract    
Assets:    
Hedge derivatives - other current assets 0.8  
Liabilities:    
Derivatives - other accrued liabilities   0.2
Fair Value, Measurements, Recurring | Commodity Contract | Quoted Prices in Active Markets (Level 1)    
Assets:    
Hedge derivatives - other current assets 0.0  
Liabilities:    
Derivatives - other accrued liabilities   0.0
Fair Value, Measurements, Recurring | Commodity Contract | Significant Other Observable Inputs (Level 2)    
Assets:    
Hedge derivatives - other current assets 0.8  
Liabilities:    
Derivatives - other accrued liabilities   0.2
Fair Value, Measurements, Recurring | Commodity Contract | Significant Unobservable Inputs (Level 3)    
Assets:    
Hedge derivatives - other current assets 0.0  
Liabilities:    
Derivatives - other accrued liabilities   0.0
Fair Value, Measurements, Recurring | Interest Rate Swap    
Assets:    
Interest rate derivatives - other long-term liabilities and other assets   8.0
Liabilities:    
Interest rate swaps - other long-term liabilities 1.5  
Fair Value, Measurements, Recurring | Interest Rate Swap | Quoted Prices in Active Markets (Level 1)    
Assets:    
Interest rate derivatives - other long-term liabilities and other assets   0.0
Liabilities:    
Interest rate swaps - other long-term liabilities 0.0  
Fair Value, Measurements, Recurring | Interest Rate Swap | Significant Other Observable Inputs (Level 2)    
Assets:    
Interest rate derivatives - other long-term liabilities and other assets   8.0
Liabilities:    
Interest rate swaps - other long-term liabilities 1.5  
Fair Value, Measurements, Recurring | Interest Rate Swap | Significant Unobservable Inputs (Level 3)    
Assets:    
Interest rate derivatives - other long-term liabilities and other assets   0.0
Liabilities:    
Interest rate swaps - other long-term liabilities 0.0  
Fair Value, Measurements, Recurring | Interest Rate Locks    
Assets:    
Interest rate derivatives - other long-term liabilities and other assets 23.9 19.1
Fair Value, Measurements, Recurring | Interest Rate Locks | Quoted Prices in Active Markets (Level 1)    
Assets:    
Interest rate derivatives - other long-term liabilities and other assets 0.0 0.0
Fair Value, Measurements, Recurring | Interest Rate Locks | Significant Other Observable Inputs (Level 2)    
Assets:    
Interest rate derivatives - other long-term liabilities and other assets 23.9 19.1
Fair Value, Measurements, Recurring | Interest Rate Locks | Significant Unobservable Inputs (Level 3)    
Assets:    
Interest rate derivatives - other long-term liabilities and other assets 0.0 0.0
Carrying Amount    
Assets:    
Total assets 123.1 152.5
Liabilities:    
Contingent consideration - other long-term liabilities 72.7 73.3
Total liabilities 74.2 73.5
Carrying Amount | Fuel Hedges    
Assets:    
Hedge derivatives - other current assets 2.6 3.0
Carrying Amount | Commodity Contract    
Assets:    
Hedge derivatives - other current assets 0.8  
Liabilities:    
Derivatives - other accrued liabilities   0.2
Carrying Amount | Interest Rate Swap    
Assets:    
Interest rate derivatives - other long-term liabilities and other assets   8.0
Liabilities:    
Interest rate swaps - other long-term liabilities 1.5  
Carrying Amount | Interest Rate Locks    
Assets:    
Interest rate derivatives - other long-term liabilities and other assets 23.9 19.1
Money market mutual funds | Fair Value, Measurements, Recurring    
Assets:    
Money market mutual funds 42.8 30.3
Money market mutual funds | Fair Value, Measurements, Recurring | Quoted Prices in Active Markets (Level 1)    
Assets:    
Money market mutual funds 42.8 30.3
Money market mutual funds | Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2)    
Assets:    
Money market mutual funds 0.0 0.0
Money market mutual funds | Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3)    
Assets:    
Money market mutual funds 0.0 0.0
Money market mutual funds | Carrying Amount    
Assets:    
Money market mutual funds 42.8 30.3
Bonds | Fair Value, Measurements, Recurring    
Assets:    
Bonds - restricted cash and marketable securities and other assets 53.0 92.1
Bonds | Fair Value, Measurements, Recurring | Quoted Prices in Active Markets (Level 1)    
Assets:    
Bonds - restricted cash and marketable securities and other assets 0.0 0.0
Bonds | Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2)    
Assets:    
Bonds - restricted cash and marketable securities and other assets 53.0 92.1
Bonds | Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3)    
Assets:    
Bonds - restricted cash and marketable securities and other assets 0.0 0.0
Bonds | Carrying Amount    
Assets:    
Bonds - restricted cash and marketable securities and other assets $ 53.0 $ 92.1