Accounting Policies - Disaggregation of Revenue (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Revenue from External Customer [Line Items]
Total revenue	$ 5,121.8	$ 4,513.7	$ 4,871.2
LTL revenue
Revenue from External Customer [Line Items]
Total revenue	4,605.9	4,093.3	4,494.0
Other revenue
Revenue from External Customer [Line Items]
Total revenue	$ 515.9	$ 420.4	$ 377.2