Business Segments - Income Statement Items (Details) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018 USD ($)	Sep. 30, 2017 USD ($)	Sep. 30, 2018 USD ($) segment	Sep. 30, 2017 USD ($)
Information concerning revenue, gross profit and income from operations by segment
Number of reportable operating business segments | segment			3
Revenue:
Total revenue	$ 10,429.5	$ 8,543.0	$ 29,761.7	$ 24,823.4
Gross profit:
Gross profit	266.7	239.9	756.3	702.3
Income from operations:
Income from operations	78.2	61.3	196.4	162.8
Aviation segment
Revenue:
Total revenue	5,025.3	3,705.8	14,218.9	10,531.6
Gross profit:
Gross profit	140.7	123.9	378.0	334.8
Land segment
Revenue:
Total revenue	2,854.4	2,770.5	8,675.3	8,117.9
Gross profit:
Gross profit	83.0	85.5	273.8	270.5
Marine segment
Revenue:
Total revenue	2,549.8	2,066.7	6,867.5	6,173.9
Gross profit:
Gross profit	43.0	30.5	104.5	97.0
Operating Segments
Income from operations:
Income from operations	98.6	79.1	256.9	218.4
Operating Segments | Aviation segment
Income from operations:
Income from operations	76.4	61.6	188.3	151.7
Operating Segments | Land segment
Income from operations:
Income from operations	7.8	13.1	37.7	46.7
Operating Segments | Marine segment
Income from operations:
Income from operations	14.4	4.3	30.9	19.9
Corporate
Income from operations:
Income from operations	$ (20.5)	$ (17.8)	$ (60.4)	$ (55.5)