Business Segments - Balance Sheet Items (Details) - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020
Accounts receivable, net:
Allowance for credit losses	$ 25.4	$ 53.8
Accounts receivable	2,032.5	1,238.4
Total assets:
Total assets	5,544.3	4,500.3
Corporate
Total assets:
Total assets	560.1	583.7
Aviation segment
Accounts receivable, net:
Allowance for credit losses	18.7	41.2
Accounts receivable	849.2	464.7
Aviation segment | Operating Segments
Total assets:
Total assets	2,222.8	1,789.5
Land segment
Accounts receivable, net:
Allowance for credit losses	3.6	5.0
Accounts receivable	556.8	394.5
Land segment | Operating Segments
Total assets:
Total assets	1,780.3	1,459.5
Marine segment
Accounts receivable, net:
Allowance for credit losses	3.0	7.6
Accounts receivable	626.6	379.2
Marine segment | Operating Segments
Total assets:
Total assets	$ 981.2	$ 667.6