Debt - Revolving Credit Facilities (Details)	Mar. 31, 2019 USD ($)
Line of Credit Facility [Line Items]
Total Commitments	$ 1,693,700,000
Total Outstanding	662,500,000
Total Available	1,008,000,000.0
Standby letters of credit issued	23,200,000
Senior Secured Domestic Revolving Credit Facility
Line of Credit Facility [Line Items]
Total Commitments	1,450,000,000.0
Total Outstanding	542,000,000.0
Total Available	884,800,000
Senior Secured International Revolving Credit Facility
Line of Credit Facility [Line Items]
Total Commitments	177,400,000
Total Outstanding	80,800,000
Total Available	96,600,000
Other International Facilities
Line of Credit Facility [Line Items]
Total Commitments	66,300,000
Total Outstanding	39,700,000
Total Available	$ 26,600,000