Business Segments - Balance Sheet Items (Details) - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Accounts receivable, net:
Accounts receivable, net	$ 2,583.4	$ 2,344.0
Total assets:
Total assets	5,723.1	5,412.6
Aviation segment
Accounts receivable, net:
Accounts receivable, net	934.3	776.0
Allowance for bad debt	9.4	6.6
Land segment
Accounts receivable, net:
Accounts receivable, net	794.0	737.5
Allowance for bad debt	7.8	8.2
Marine segment
Accounts receivable, net:
Accounts receivable, net	855.1	830.5
Allowance for bad debt	11.1	10.2
Operating Segments | Aviation segment
Total assets:
Total assets	2,242.3	2,050.6
Operating Segments | Land segment
Total assets:
Total assets	2,014.7	1,928.5
Operating Segments | Marine segment
Total assets:
Total assets	1,309.6	1,287.7
Corporate
Total assets:
Total assets	$ 156.4	$ 145.8