Business Segments - Income Statement Items (Details) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018 USD ($)	Jun. 30, 2017 USD ($)	Jun. 30, 2018 USD ($) segment	Jun. 30, 2017 USD ($)
Information concerning revenue, gross profit and income from operations by segment
Number of reportable operating business segments | segment			3
Revenue:
Total revenue	$ 10,150.8	$ 8,086.2	$ 19,332.2	$ 16,280.4
Gross profit:
Gross profit	246.2	231.0	489.6	462.4
Income from operations:
Income from operations	61.1	51.2	118.3	101.6
Aviation segment
Revenue:
Total revenue	4,900.7	3,508.4	9,193.6	6,825.8
Gross profit:
Gross profit	127.4	110.9	237.3	210.8
Land segment
Revenue:
Total revenue	2,960.2	2,564.0	5,820.9	5,347.4
Gross profit:
Gross profit	88.6	87.2	190.8	185.0
Marine segment
Revenue:
Total revenue	2,289.9	2,013.8	4,317.7	4,107.3
Gross profit:
Gross profit	30.2	32.9	61.5	66.6
Operating Segments
Income from operations:
Income from operations	82.3	69.2	158.3	139.3
Operating Segments | Aviation segment
Income from operations:
Income from operations	64.2	49.7	112.0	90.2
Operating Segments | Land segment
Income from operations:
Income from operations	10.2	12.2	29.9	33.6
Operating Segments | Marine segment
Income from operations:
Income from operations	7.9	7.2	16.4	15.5
Corporate
Income from operations:
Income from operations	$ (21.2)	$ (17.9)	$ (40.0)	$ (37.7)