Debt - Lines of Credit and Other Debt Facilities (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Total debt and capital lease obligations	$ 5,376,000,000.0	$ 5,447,200,000
Revolving Credit Facility
Debt Instrument [Line Items]
Outstanding letters of credit	10,200,000	19,300,000
Reduction in borrowings	9,700,000	18,600,000
Line of Credit | Revolving Credit Facility
Debt Instrument [Line Items]
Total debt and capital lease obligations	25,000,000.0	0
Line of Credit | Lines of Credit and Revolving Lines of Credit
Debt Instrument [Line Items]
Total debt and capital lease obligations	25,000,000.0	0
Remaining borrowing capacity	$ 481,000,000	$ 509,000,000