Business Segments - Balance Sheet Items (Details) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Accounts receivable, net:
Allowance for credit losses	$ 43.8	$ 53.8
Accounts receivable, net of allowance for credit losses of $43.8 million and $53.8 million as of March 31, 2021 and December 31, 2020, respectively	1,669.2	1,238.4
Total assets:
Total assets	4,925.4	4,500.3
Corporate
Total assets:
Total assets	556.1	583.7
Aviation segment
Accounts receivable, net:
Allowance for credit losses	31.0	41.2
Accounts receivable, net of allowance for credit losses of $43.8 million and $53.8 million as of March 31, 2021 and December 31, 2020, respectively	570.0	464.7
Aviation segment | Operating Segments
Total assets:
Total assets	1,868.5	1,789.5
Land segment
Accounts receivable, net:
Allowance for credit losses	4.6	5.0
Accounts receivable, net of allowance for credit losses of $43.8 million and $53.8 million as of March 31, 2021 and December 31, 2020, respectively	520.9	394.5
Land segment | Operating Segments
Total assets:
Total assets	1,598.0	1,459.5
Marine segment
Accounts receivable, net:
Allowance for credit losses	8.2	7.6
Accounts receivable, net of allowance for credit losses of $43.8 million and $53.8 million as of March 31, 2021 and December 31, 2020, respectively	578.4	379.2
Marine segment | Operating Segments
Total assets:
Total assets	$ 902.7	$ 667.6